• Camera – it is so awkward to force 3rd party apps to switch out to the camera app, take a picture, then switch back and pick a photo from the photo roll in order to get a picture.
• Calendar – We would love to have access to the calendar event creation so when our iPhone list application creates a task with a due date we can add it to iPhone’s native calendar.  Without this access a due date in our lists app is pretty meaningless, because we can’t even generate a notification or alarm because we can’t run in the background.
• Real background app – See above.  Without true background processes, it is not possible to write a simple alarm clock.  Apple’s proposed push architecture is good enough for some apps but it won’t work if the phone is out of coverage.  So it is not possible to write a reliable real time alert, such as the due date example.  I know the stability of the iPhone is important, maybe we can get access to the alarm clock so we can set app specific alerts and notifications.
• SMS – SMS is the most direct way for users to send information to another phon e in real time.  It would open up a host of possibilities if social apps can use SMS to message another phone.
• Music library, phone, etc.

Apple’s own applications can do things that can’t be done by 3rd party.  I hope they will gradually remove those artificial limitations to level the playing field.