Apple’s annual WWDC dev conference is underway, and while we can’t confirm whether or not the next iPhone is in yet, the company revealed some rather important figures concerning the App Store.

Twitter has about 120 million accounts according to a recent survey, and Facebook is leading the charge with over 900 million users.  Apple CEO Tim Cook revealed today that the App Store belongs to the same list as the two social media titans: it apparently hosts no less than 400 million accounts, which accounted for 30 billion downloads to date. There is a total of 650,000 apps available right now, about a third of which developed for the iPad, and they generated $5 billion in revenue for their creators.

Perhaps more notable is the fact that Cook provided some details about Apple’s plans to expand even further. By the end of this month the App Store will be accessible from 155 countries.

“What we do together is much more important than any set of numbers could reflect. Our Goal has always been to do great work and make a difference in other people’s lives.”

The competition between the App Store and the social networking scene is not limited to population alone – Facebook is looking in on the action, and recently launched its own mobile marketplace. The App Center currently features t 600 applications for both Android and iOS, and each and every single is somehow integrated with the platform.