"Looking just at the OTA eligible users we again see a promising future for iOS developers. Nearly 80% of users are on the latest version within 15 days." http://david-smith.org/blog/2012/03/10/ios-5-dot-1-upgrade-stats/index.html#march21
Yes, but put out an update with a bug in iOS 3.0 or something, and every one of those 30 people worldwide still on 3.0 will ding you in your app reviews! If only we can figure out a reliable way to determine when to safely bump up the minimum iOS requirements without making the people who never update their OS unhappy and descending to complain.
You could remove support for for anything older the 3GS, if you'd be prepared to loose that small demographic.
Excuse me if I take his stats with a nice big grain of salt. He's basing this on the downloads of his app, which he says has 100K downloads a week. He provides no proof for this, we simply have to take his word for it.
