I thought the Black Diamond Switchback was just an average run-of-the-mill UMPC that came in a rugged case, until I learned of the module system that they are using. This UMPC has well over 20 modules that can be easily swapped onto the UMPC, including a breathalyzer. Some of the other modules include terrestrial radio, USB, etc.
The "ruggedness" of the UMPC comes from the housing that meets the military standards for shocks, vibrations and extreme temperatures. Unfortunately, it has a weak, 2-hour battery life and is powered by one of those Intel Celeries. At least it has a true, hardware keyboard integrated, which can't be said about the other UMPCs out there. A Black Diamond rep told Gearlog that the Switchback's price will be consistent with other rugged devices—so expensive as hell.