In early May, we reported that Apple is bringing a long-awaited over-the-air iOS software update feature to iOS 5. Sure enough, Apple announced the feature as a part of their iOS devices become PC-free initiative, but the keynote did not specifically mention that updates over 3G are coming (even though the phone showed a 3G symbol). Now, in line with our earlier report, we have discovered – through the iOS 5 SDK – that iOS 5 will, in fact, support over-the-air firmware upgrades over 3G networks. (Thanks, Sonny Dickson)

There is a catch, though. Based on these SDK findings, it looks like only certain iOS updates will support downloads over 3G. Perhaps small point upgrades like 5.1.1 will come over 3G but 5.1 will have to come over WiFi. Or perhaps 5.1 can come over 3G but 6.0 has to be downloaded over a WiFi network.

Another catch will likely be carrier support, but that is unconfirmed. iOS 5 will also only begin the software update process if your phone has enough battery life and storage (looks like Apple will expect 500 MB of necessary storage per delta update) to make it the whole way through.