There's a lot of PDAs and Smartphones (about 100 different models) on the market now that can be used with Run.GPS. Basically, the requirements are the following:
Operating System
Windows Mobile 2003, Windows Mobile 5 or Windows Mobile 6
both Pocket PC and Smartphone editions are supported
Screen
Run.GPS Trainer UV now supports almost all sizes and orientations
Memory
you need about 10 MB of free memory to install Run.GPS
If you buy a new Pocket PC, we recommend it should have the following:
built-in GPS
built-in camera (Run.GPS allows you to "geo-code" your images, i.e. to automatically place them on the map)
phone capabilities (not only in case of an emergency very useful, - you can also upload and download to and from the GPS-Sport portal using a wireless Internet connection)
WLAN (to upload/download when you're at home or near a hotspot, surf the Internet or use Skype)
There are already some devices that have all of these features, for instance the HTC P3300 (=O2 Xda Orbit).