I would just like to see Apple make jailbreaking nearly unnecessary in 4.0. Which means incorporating:
- multitasking for all apps, not just their own
- theming. The default theme is nice, but customization would be better
- downloading & saving of attachments. How they've ignored this for as long as they have is inexcusable, especially with the plethora of apps that can read & edit documents of all kinds
- downloading of files from Safari. Again, pretty weak of them to have ignored this feature
- a section of the file system that is available to users, for the aforementioned downloading and saving of files. This section should also be available to all apps
- something, anything other than the currently useless home screen
Do this, and many people would have little need for jailbreaking, which I'm sure would please Apple.