1) Framework for integration with iTunes for syncing content & data.
2) Ability for developers to submit their apps to a more strenuous review process to get true background app functionality.
3) Theme support (sounds, icons, etc) I'd have no problem with this being a paid first party Apple app.
4) Folder support for sorting applications. Maybe something like Smart Folders that looks at the AppStore category to automatically sort things.
5) A2DP, Bluetooth keyboard support, bluetooth file transfers
6) Native support for OSX Screen Sharing & integration with Back To My Mac
7) Ascending ringtone volume level option.
8) Text-to-Speech options. For example, on an incoming e-mail text-to-speech who it's from and the subject.
9) More dock space (scale the icons down as more items are added)
10) Ability to use the iPhone itself as a remote speaker.