Twitter Now Valued at $7 Billion [REPORT]

Twitter's valuation has almost doubled in the last seven months, according to a report from The Wall Street Journal.

The Journal says Twitter is busy raising hundreds of millions of dollars, at a valuation as high as $7 billion. In December, the same company was valued at just $3.7 billion in a $200 million round of funding led by Kleiner Perkins Caufield & Byers.

Why the increase in valuation? Twitter, once a site without much of a business plan, is now a social media staple with a growing number of revenue streams.

Twitter introduced promoted tweets and trends last year, which proved to be the company's first notable revenue source. Recently, eMarketer predicted that Twitter would triple its advertising revenue to $150 million in 2011. Last month we learned that Twitter plans to introduce promoted tweets into users' timelines by the fall.

In October, it announced that it would develop a self-serve tool that would also allow small businesses to get in on the Twitter advertising game.

As its peers in the social world -- like LinkedIn -- go public, Twitter is instead focusing on strengthening its executive team and building a solid advertising business.