Launched this morning, comScore’s “Media Metrix Multi-platform” shakes up the existing rankings in some dramatic ways. Music site Pandora, for instance, jumps from #61 on the list to #23 while ESPN jumped four slots to #19. The sports site’s jump comes thanks to the inclusion of the 35 percent of people who consume ESPN only on mobile, not desktop, devices. Other big winners included Amazon, Wal-Mart and e-Bay; the three companies all had an incremental mobile audience of more than 20 percent. Here’s a look at some of the US numbers:

The new metrics, which are based on a mix of internet tagging and census methods, also reveal that the number of so-called “unique visitors” to websites are much higher when mobile figures are included. For instance, comScore says that more than 10 websites have more than 100 million visitors when mobile stats are included (compared to only six such sites if only desktop figures are used).

comScore says its new analytics system also suggests other important lessons in how publishers and advertisers measure a website’s success. In particular, the company recommends valuing “engagement” (time spent on a site) over page views. Under the engagement method, comScore says Facebook ranked first in the mobile category.

comScore’s new metrics system is still in beta but, given that mobile consumption is an irreversible phenomenon, it seems inevitable that publishers and advertisers will have to get accustomed to the new measurements. The growing predominance of mobile also poses challenge to publishers and advertisers who are still struggling out how to extract money from smaller screens.

While comScore has offered mobile measurement tools in the past, the significance of the new product is that provides an unduplicated tally across all platforms. More details are available here at comScore’s release.

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