Within a week of launch, Apple® announced that iPhone™ and iPod® touch users have already downloaded more than 10 million applications from its groundbreaking new App Store since its launch late last week. Developers have created a wide array of innovative mobile applications ranging from games to location-based social networking to medical applications to enterprise productivity tools. Users can wirelessly download applications directly onto their iPhone or iPod touch* and start using them immediately. More than 800 native applications are now available on the App Store, with more than 200 offered for free and more than 90 percent priced at less than $10.

WIthin a month of launch, the App Store has recorded a record 60M downloads and is anticipating a $1B revenue generator (which is subject to revenue sharing with developers).

The prediction is that Apple App Store will see at least 100M downloads by end of September 11, 2008 (2nd month performance).

Reference articles:
http://www.apple.com/pr/library/2008/07/14appstore.html
http://online.wsj.com/article/SB121842341491928977.html