
By comparison, the Android Market has just over 200,000 apps, Nokia's now defunct Ovi Store had 50,000 and BlackBerry World and Windows Phone 7 Marketplace both have under 25,000.
It is important to note that active apps are just about 400,000 due to replacements and removals, however.
Thanks to http://www.facebook.com/500kapps, a joint effort by Chomp, 148apps and Chillingo, we have an awesome infographic about the milestone, available here:

Written by: Andre Yoskowitz @ 24 May 2011 11:23