Apple had sold more than 400 million iOS devices as of June 2012 according to CEO Tim Cook. Cook made the announcement during the iPhone 5 launch event today at the Yerba Buena Center in San Francisco. The numbers put Apple neck-and-neck with Android, which according to a Sept. 12 tweet from Google senior vice president Andy Rubin, has seen more than 500 million device activations to date.

Cook also revealed there are now more than 700,000 apps in the App Store, 250,000 of which are designed specifically for the iPad. The average iTunes App Store customer uses more than 100 apps, and that 90 percent of the apps found in the iTunes App Store received new downloads every month — a statistic likely designed to assuage developer’s concerns over discoverability in the notoriously crowded App Store.

While the information does mean that even apps far off the charts are able to generate a few downloads every month, the vast majority of App Sore downloads belong to the apps fortunate enough to appear on the highly visible top ranked paid, free and grossing app charts. Discoverability issues in the iTunes App Store have meant that some developers employ multi-million dollar app marketing budgets to ensure their apps are found. In the past, iOS developers have also tried to game the system through offer walls and download bots.

Later in the presentation, Apple’s senior vice president of internet software and services Eddy Cue revealed the company has integrated Facebook and Twitter into the iTunes App Store, an improvement likely designed to improve discoverability through social media.