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New SMS tones! Oh my goodness the current ones are getting BORING! Especially since I only like one of them as it is.

Also... I would like Apple iChat.

That's all.
 
Notifications for e-mail would be helpful and I'm surprised they're not present in the current version of the OS.

Rules for e-mail would also be great.

I'd also like to see more extensive use of data tags across applications.

More speculatively, I see can see the iPhone becoming a truly mobile computer so better support for higher resolution displays then is currently available via the A/V cable would be great as well as support for Bluetooth keyboards. This would facilitate more business related applications.

Perhaps a future version of the iPhone will be your computer. You dock it and its OS appears on the monitor.
 
Quick reply/send

I hate quitting whatever application I'm in just so I can reply to or send a text.

I completely agree with this. I hate the fact that if I am doing anything in the phone and I reply to a text, then I have to kick back out to the home screen and find the app again and restart it. The 3G S makes the load time much better but still the process could be improved. This should be a pretty easy software fix.
 
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