I started using an unlocked HTC G1 (the Google phone) a few weeks ago and think that I'm going to keep on using it instead of my iPhone 3G. Amongst many other nice things, it has satisfied my need for a good GPS device for geotagging photos. Between the ability to run applications continuously in the background and a removable battery (that goes for eight buck on eBay), it can handle running for a week straight and replace my standalone GPS for hiking and backpacking trips. The nice integration with EveryTrail (here's a track from walking back to the car today) is also a plus.