Techchrunch did some app sales analysis:
In this scenario, the average sales were 11,625 total units, averaging 44 copies/day. Approximately 23% of apps sold less than 1000 units from launch (ranging from 12 to 370 days in the App Store). Further, 56% of apps sold less than or equal to 10,000 units, while 90% sold less than 100,000 units, with the remaining 10% achieving sales of 127,000 – 3,000,000 units.
Interesting. Relatively low numbers on the one hand, but really encouraging on the other.