Nabbed an iPhone 3G for my b-day a couple months ago, really diggin' it. The applications you can download are getting better and better. I've had one on my wish list that integrates w/ the gps on the phone and puts my saddle time on a map, including speeds and altitude and other nifty things.
Bingo - TrailGuru to the rescue.
I dorked out, downloaded the app over lunch, and turned it on for the ride home. It's a peach. Check out my tiny commute home here.