The good news:
- Push (background) notifications for apps (e.g., you can log into all your accounts on the Meebo app then close the app – it will notify you when you get a message)
- Cut, copy & paste text in any app, undo with a shake
- SMS app is now “Messages” app
- MMS support (pictures in text messages)
- Can forward and delete individual messages
- Can send and receive contact cards, audio files, locations
- Landscape (wide) keyboard for all Apple apps (Mail, Safari, etc.)
- Peer-to-peer wireless gaming
- A2DP (stereo over bluetooth)
- Spotlight – adds search to all key apps (Address Book, Mail, Calendar. iPod, Notes)
- Sync notes to your computer
- Multi-photo emailing
- Support for turn-by-turn GPS
- Voice Memo app
- Calendar app subscriptions (CalDAV, Exchange support)
- Downloadable content for apps
- Communication with iPhone accessories (possibility of a gamepad attachment?)
The bad news: won’t be released until sometime “this summer”. 
iPhones are cool, I don’t own a iPhone