You can watch the SDK launch event video where full details were given on what was coming in 2.0, at:
http://events.apple.com.edgesuite.ne...rnal=fj2l3s9dm
The two biggest things are the App Store and full Exchange Activesync support.
Since that event, a lot of solid sources (developers testing beta builds of the new firmware) have spotted other interesting items like: Contacts search, ability to download images from Safari, parental controls and others I can't recall right now ...