I'll kick it off with some ideas I've come up with. I'll no doubt think of others. Hopefully other Geekzoners will chime in with ideas of their own. Maybe just maybe some of these might end up being implemented.

Bluetooth audio support for Nokia Maps on Symbian 3
Allow the turn by turn instructions to be played over the radio or other paired Bluetooth device as is possible on earlier versions of Symbian.
Ability to syncronise documents/files with a PC
One feature I used a lot with my PDA was the ability to synchronise documents between my PDA and PC. I could edit the document in either place and then synchronise to update on the other device. I use my phone as my PDA now and this would be a handy feature to have incorporated into Nokia Suite.
Provide for shortcuts directly to documents
The ability to be able to open or go to a document directly from a home screen short cut would be very handy. It is possible to do this with SPB shell, having this as a standard function would be very useful.
Improvements for texting Symbian 3
I still find using the alpha numeric keyboard and predictive texting the best option when texting in portrait mode. My fingers are average size but I find I regularly hit the bottom row of buttons, especially the menu key, by mistake, moving these keys to the top of the text box out of the way would be better.
When replying to a text there is one more step than necessary in my opinion. Currently when you hit the reply button you end up on a page where you are asked to "tap to write" which opens up the box where you write your message. Why not go directly to the message box when you hit the reply button abd cut out one step?