Here are the bulletin points I was able to fetch from several feeds:
Multitasking (the Apple way without big chunks of performance or battery life going down with it)
Folders (you can have now more then 2000 apps on the device)
Organise your inbox by threads
Open email attachments with apps
iBooks for the iPhone!!!!!!! I cannot stress enough how lucky this makes me. It also wirelessly syncs with your ipad. Buy it once read it everywhere.
Apples own social networking for games called Game Center. Xbox Live for the iPhone No more open feint, crytal, plus+, etc. Yeah! I called it back in the days and El Jobso answered! Can anyone confirm VoIP?
Apples iAd service. (Since it's build into the OS you won't get out of your app when you "click" on a add)