interesting, but I would love to know the amount of applications in iOS / Android with installation base >= N (with N something like 100). I doubt such a data is available unfortunately.
However the App store is not making a good job at all trying to help users to discover "long tail" applications that are well designed and useful. It's all about stressing the few tops that everybody already know. I hope the Android market is better in this regard.
I can't give you an exact answer, but I can tell you this... out of the 224,133 apps I track in the android market, here is the breakdown of how many installs they have as of this morning: http://dl.dropbox.com/u/131/installs.csv
I believe AppBrain released some stats not too long ago, the vast majority of Apps do verry poorly if I remember correctly, will try and find the report.
Two of those 400k Android apps are mine, one is free with ads and restricted, and the other is paid. So duplicates of the same app have to be considered. And most of them are junk apps, poorly built, thrown together by some experimenting devs testing the water... Like me.
However the App store is not making a good job at all trying to help users to discover "long tail" applications that are well designed and useful. It's all about stressing the few tops that everybody already know. I hope the Android market is better in this regard.