NOTHING! There is no difference between the 4 Releases. The changes were only for the iPhone's benefit. It was designed for the iPhone! Which was 8 GB (Some 4) He didn't code it for anything else. The App probably has a hard time recognizing the 16 GB of the iPod Touch. It does not matter which version of ZiPhone you work. They're all the same. I hope this helps cause I'm kinda tired of repeating myself.