I think Apple will release a BIG iPhone update - after Leopard.
This will allow them to tie in a lot of new things (or at least use the same technology, which they couldn't very well do until Leopard is released) - To-Do syncing, Coverflow for file browsing (therefore adding an accessible file-manager to the iPhone), system-wide Spotlight search, iChat update (perhaps).
It makes sense...
And, while they're at it, sort out simple things like:-
-Speaker volume too low when in anything but a silent/very quiet environment
-Ability to reduce/increase specific alert volumes and even turn them off, using the volume buttons (not just the ringer)
-Forward SMS messages
-iCal revamp inc. better repeat options, dragging to different days to duplicate or change (it's quite slow to change dates/times, too many screen to go through and it's fairly slow to respond), add to/see multiple colour-coded calendars
-Copy/paste for text and the ability to select, etc.
To be honest, before I got my iPhone I thought more things would bug me (lack of alert profiles, changeable alerts etc.)...but they don't , I've worked around most limitations - and for the most part, I love it