Android
Differences
Most people really just want it so that they can play Farmville (a Flash game) on Facebook from their phones.
Candall said:
Flash was the big one. You'll also have access to apps that were written specifically for 2.2, so the Android Market's a bit more open to you. I think there were other changes, but my understanding is that they're mostly under-the-hood type tinkerings.
Saving apps to the SD card instead of using the internal memory is the other big one. i'd love to have that option on my phone right now.