A pretty good number considering that the Mac App Store requires updating to Snow Leopard 10.6.6 before you can access the store and its contents.
How does this compare to the iOS App Store’s launch? Well, it’s significantly less. The iOS App Store commanded 10 million downloads in the first weekend, which averages about 5 million per day for all you math-impared people out there. If Apple gets another million downloads today it will only be 20% of the sales made through the iOS App Store back in 2008.
This is not entirely surprising considering that there is still a significant number of Macs that are not running Snow Leopard, so I think this number will continue to grow and become more profitable as time marches on.