In 2011, Twitter’s advertising revenues grew 233 percent, and LinkedIn’s sales were up 95 percent, and both are set to see more growth in the years ahead.

Meanwhile, just days before an expected IPO, Facebook has solidified its lead in online display advertising not just in social networking, but over all online properties.

According to figures out from eMarketer today, Twitter’s revenue from advertising was a mere $139.5 million in 2011, but that was actually up by 233 percent over 2010. The analysts believe that international growth will further push that number up to $259.9 million this year, a rise of 83 percent.

Meanwhile, LinkedIn (NYSE: LNKD) actually rounded off 2011 with more ad revenues than Twitter, with $154.6 million in sales. But it will see much more modest growth in the years ahead, with that figure only going up by 46 percent in 2012 to $226 million. At the moment, LinkedIn is proving to have the bigger international profile when it comes to advertising, with some 32 percent of its ad revenues expected to come from outside the U.S. in 2012, versus only 10 percent for Twitter. (Full tables with forecasts at the bottom of this post.)

Today, Twitter has some 300 million users compared to 135 million for LinkedIn, and so some of Twitter’s gain on LinkedIn in ad revenues could be down to that simple fact. User numbers may, too, be the reason why Twitter will widen its lead in ad sales even further in the years ahead. By 2014, eMarketer predicts that Twitter will have annual ad revenues of $540 million compared to $405.6 million for LinkedIn.

But even those 2014 figures are still less than 15 percent of what Facebook makes in advertising at the moment, mostly in the form of display ads.

With revenues of $4.27 billion in 2011, $3.8 billion of that from advertising (eMarketer via WSJ) Facebook is the social network to beat. That’s true today but also in the future, as it only continues to enhance the services it offers to engage users and keep them on the site for longer.

According to figures provided by comScore (NSDQ: SCOR), in the U.S. Facebook has widened its lead in the display-advertising market in 2011. It now has 27.9 percent of that market, compared to 21 percent the year before. That puts Facebook significantly ahead of the next-closest competitor in display, Yahoo (NSDQ: YHOO), which is at 11 percent. The full figures for 2011 and how they compare to 2010:

In UK figures provided also by comScore, the leadership of Facebook is even stronger, with over 30 percent of the market for 2011 in terms of revenues.

With Twitter and LinkedIn, it is too early to tell which social network’s ad formats prove to be the more engaging, and more attractive to media buyers.

For now, it looks like LinkedIn is winning at least in the variety stakes, with ads to match particular user profiles and professions, as well as different areas for placement (Profile Page, Home Page, Inbox, Search Results Page and Groups) and formats. Twitter has, so far, concentrated on promoted tweets as the basis of their advertising. LinkedIn offers advertisers a self-serve platform for its services. Twitter launched its ad platform only in November 2011, and as eMarketer analyst Debra Aho Wiliamson puts it, the “verdict is still out” on whether it will gain traction.

But over the last five years — with the mainstream arrival of HDTV — researchers note that half of US households have purchased an HDTV. That would suggest that the upgrade cycle has increased considerably over that timespan.

Fair enough.

But what’s fascinating is how Lawler’s sources want to extend this accelerating trend into the future. Having recently discovered the conventional wisdom based on trend was incorrect, they immediately create a new conventional wisdom based on even more limited data.

First, they assume that TV upgrade cycles might end up looking like computing or mobile phone upgrade cycles. “HDTVs might not have reached the two-year replacement cycle that most consumers have for their mobile phones, but consumers are definitely making HDTV purchase decisions more often,” Lawler writes. “Those decisions are happening more along the lines of the three- to five-year cycles that consumers have for computing devices.”

Then, a shopping site spokesperson argues that it is the increasing quality of TVs that are driving upgrades and that higher quality will equal even faster upgrades.

“Low prices make it tempting for people to replace their TV sets more often. We estimate that today’s household replaces it’s TV set every four to five years. If TVs continue to get bigger, better and significantly cheaper, we estimate that people will replace them more often,” Retrevo spokesperson Jennifer Jacobson wrote in an email.

Finally, Lawler offers an argument for how TV quality could continue to increase, even though visual quality has basically reached the limits of the human eye.

And as time goes on, there might be another reason for consumers to begin replacing their TV sets — or at least, the TV sets in their living rooms: They might soon become obsolete. As more and more “smart” TVs enter the market, the applications and app development frameworks available on the first generation of Internet-ready televisions will find themselves eclipsed by more powerful and attractive options.

Now, I have no reason to doubt the idea that people have replaced their televisions more quickly in the last five years than in the years before that. But I do doubt all the rest of this reasoning.

First, HD is a special technology. It takes screen resolution from below what the human eye can see to just about as good as anyone can notice. Perhaps that was a generation-level sales point that won’t come around again.

Second, there’s no reason to expect that TVs should follow the purchase cycles of phones or computers. Sure, they’re both types of electronics, but so what?

Third, absent a compelling visual reason, it’s unclear that people will continue to purchase televisions at a faster and faster rate. That people want a better picture is well-established. That people want a “connected” television is far less so, and there are many other ways to achieve the same service without having it built into the television.

Fourth, and most importantly, seeing a change in a trend shouldn’t just get us to immediately adopt a new dogma. It should make us step back and question how well we know what’s going on and whether we can trust our trend forecasting. Lawler’s thesis may be correct, but it might not be What troubles me is the assumption that a nascent trend will hold. If a long-established trend can break down, what gives us confidence that a more recent one should accelerate?

This article originally appeared in The Atlantic.

Press releases from Virgin and Square do not give any indication of how much money Branson has invested in the company, which was started by Twitter founder and (current) executive chairman Jack Dorsey. We have contacted Square, Dorsey and Branson to ask and will update this post as we learn more.

Square raised $100 million at the end of June in a round led by Kleiner Perkins Caufield & Byers. At the time, that valued the company at $1 billion.

Square built a business initially on an iPhone-based mobile payments service that is now avaialbe for both iOS and Android devices. It provides a square-shaped dongle to merchants, who can plug the device into a phone to make instant card transactions. Some 800,000 merchants in the U.S. are now using the dongles, and there are around $2 billion in payments processed annually through the platform. At the standard 2.75 percent commission that Square charges merchants, that works out to annuals revenues of $55 million from those transactions going to Square.

Last week, the company upgraded its payment app, Card Case, which now uses geofencing technology built into smartphones to let a user make purchases without even presenting the device. About 20,000 merchants have signed up to work with the Card Case app to date.

How will Richard Branson’s investment in Square figure in the company’s strategy? It seems unlikely that Branson has taken an interest in Square as a simple financial investment. Rather, Branson could prove to be a key figure for Square as it looks to make its payment services more ubiquitous.

Square has said it plans to launch in international markets in 2012, and Branson’s international Virgin empire could help with that.

Not only does Virgin operate national and international airlines, but it has a number of other travel interests, including train services in the UK. It also runs a number of financial services, as well as gyms, mobile operators and a pay-TV company: all opportunities to increase the number of Square transactions and give more exposure to the brand on a global basis.