|Image by Ryan Cash - ryancash.net|
Well I'm not sure what's worst. Android got a lot of heat about fragmentation in their software. It now seems Apple is trying to hide in it's shadows with fragmentation that can be potentially be more costly to the end user.
When looking for accessories like cases you'll have to now keep in mind the following versions.
Black AT&T iPhone 4
White AT&T iPhone 4 - Thicker
Black Verizon iPhone 4 - Buttons moved slightly
White Verizon iPhone 4 - Buttons moved slightly, thicker
White iPhone 4 Slightly Thicker Than Black iPhone 4 - Mac Rumors