The one feature that most of us iPhone owners want is native instant messaging. With the upcoming SDK release, instant messaging apps will most likely not be able to run in the background (in other words, they may not receive messages when the phone is sleeping or doing other things). However, AppleInsider is reporting on an Apple patent for instant messaging on the iPhone that was filed in August of last year, but just granted in March of this year.
The drawing included with the patent filing looks identical to the SMS application on the iPhone, with some key differences, one of which is word suggestions that appear as bubbles above the keyboard. AppleInsider also reports that this service could be used as a substitute for MMS (multi media messaging) which the current iPhone is lacking.
You can read the full patent filing on the USPTO's website.