Now because this is not out for the consumer yet I will be talking about my opinion and not the specifications.
1: Most anticipated was wallpaper behind the icons. Good thing we got that or else I would have disappointed in Apple.
2: Multi-tasking is now precent and this is great. I actually jail-broke my iTouch because I wanted multi-tasking so bad. But now it is here and that satisfies me.
3: Folders: Now you can hold all your favorite apps and not have to delete them because you can now exceed 2,000 apps instead of 180 or what ever it was before.
4: There are many other things included but I am not going in depth. These include: Universal inbox, threaded messaging, no more Apple servers, universal online game playing, iAds, ect.
Now here is the big question: what i-devices will it be for.
Well, all of them but only the iPhone 3GS and the iPod Touch 3rd generation will get the key feature, multi-tasking.