The monumental amount of apps downloaded goes beyond just demonstrating the success of the store. It also goes to show how eager and willing people are to extend the functionality of their phone. With an estimated 50 million iPhone and iPod Touch owners around the world, that gives an average of about 40 downloads per device. Repeat downloads, free apps and many other things definitely skew that figure, but even halved, that demand is significant.
Where will it go from here? With such an insatiable demand, they pretty much have free reign. It makes me wonder what Google's strategy is for luring people away to join the Android camp.