Twitter may give the impression that it’s in no rush to make money, but the company certainly seems confident that it will start bringing in money soon. Earlier this year, Twitter expected revenue to reach $140 million by the end of 2010 and $1.54 billion in 2013, according to documents leaked to TechCrunch. (We won’t get into the ethical/legal debate about the documents hack, although Twitter says it is talking with its lawyers about the implications on the parties involved. Read more below). The documents also show that the social networking site projected it would bring in $400,000 in revenue this quarter—and $4 million during the fourth quarter. So far, Twitter’s only confirmed revenue stream has been its relationship with ExecTweets, which it promotes.

The leaked documents also show that Twitter has some heady projections for its membership. The site expects one billion users by 2013 (It had about 23 million uniques in June, according to Compete.com). A caveat: Via TechCrunch, Twitter says that while the document is authentic, it “was never an official document and it certainly is no longer accurate.” Considering that the documents show that Twitter only expected 25 million users by the end of the year, perhaps its projections are now even greater.

Here’s more from the statement Twitter posted on its blog: “We are in touch with our legal counsel about what this theft means for Twitter, the hacker, and anyone who accepts and subsequently shares or publishes these stolen documents. We’re not sure yet exactly what the implications are for folks who choose to get involved at this point but when we learn more and are able to share more, we will.”

• Twitter Considers E-Commerce As A Possible Revenue Stream