I use MyTracks on an android phone (was using a MyTouch 3G until I got my Nexus One).

Battery life can be an issue, I use up about 30% on my one hour commute. I picked up an 18000 mAh battery pack for long rides. I did a 200km brevet last month in 10:48, and the power pack was still at 3/4 capacity (and the phone was at 100%). Based on that I should be good for over 40 hours, which ought to get me through a 600km brevet. The biggest downside is that it weighs half a pound. But they make smaller ones if you don't need that much capacity.

I can upload rides from MyTracks to Google Maps and the data to a speadsheet on Google Docs. The map of my 200k brevet is here. Clicking on the end marker pulls up the details and elevation graph.

Keith