Here are a few feature requests we would like to see added to the iPhone at some point:
3G. not that it is available in my area, but some day it will be!
The iPod application includes a handy volume control slider, but does not appear to include a method for changing the playing location of the current audio track (rewind/fast-forward/jump to point). This feature does appear in the video player.
GPS with integration into Google Maps
Use the built in camera to record video.
Push email from Google. Not totally in Apple's control because Google does not currently offer IMAP. When/if Google adds this feature it would be nice to know that the phone will support it.
Steve pointed out that iPhone parses phone numbers in email messages, how about parsing street addresses with a magical import into Google Maps?
Support for multiple email accounts. This feature may already be present, I can't tell from the demos. These days people have many email accounts including work and one or more Gmail, Yahoo!, and Hotmail accounts.
Display Favicon.ico (the little icon/logo next to the site address in most browsers) image on the bookmarks screen and the change page screen.
Flash videos supported: At present, iPhone seems only supports mp4, h.264, mp3, aac. If it supports Flash files, iPhone will be more popular. Flash is working its way into all of todays popular sites (YouTube, MySpace, Google Talk (web), Yahoo! Messenger (web), etc)
Third-party software: The list of applications available for Windows Mobile and Palm is huge! I am sure many of the Mac developers out there would love the opportunity to develop/sell applications that run on the iPhone like games, video conversion, DVD to iPhone software, music data recovery, media editor, etc.
There has been some rumors of an Apple developed spreadsheet application for Mac. It would be nice if there was a mini-spreadsheet program for viewing/editing simple spreadsheets. The same thing goes for Word documents (as you might guess Microsoft makes mini-versions of these applications available on their phone OS).
Flash videos supported: At present, iPhone seems only supports mp4, h.264, mp3, aac. If it supports Flash files, iPhone will be more popular. Flash is working its way into all of todays popular sites (YouTube, MySpace, Google Talk (web), Yahoo! Messenger (web), etc)