While Twitter may be getting the majority of the press in the Facebook-Twitter competition, Facebook’s still the 800 pound gorilla in the room. Today the world’s largest social network made that clear by announcing that they now have more than 300 million users.

In a blog post, Facebook Founder and CEO Mark Zuckerberg highlighted the social network’s constant growth and also announced that the company was self-sustaining and cash-flow positive, not a small feat by any means considering the relative trouble they’ve had monetizing. Being able to generate a profit opens the door to many possibilities, including an IPO.

The announcement also means that Facebook grew from 200 million users to 300 million in just over 5 months. It took 8 months to reach 200 million from 100 million, and it took years to reach the 100 million user milestone. This is a company that is growing faster, not slower, than its competition.

As the company continues its all-out assault on Twitter, it’s easy to forget that it simply has more users than its upstart rival. By the end of the year, there should be 18 million Twitter users. That’s not even 1/15 of the current size of Facebook.

If Facebook continues to open up its platform and adopt Twitter’s best features, it could spell real trouble for the Twitterverse. The world’s largest social network is on the warpath.