It has. It uses earths magnetic field as a reference to its orientation (to the magnetic poles).

Here's something that NASA has come out with: http://www.patentstorm.us/patents/6114995/fulltext.html

Basically what Darwin does, is emulate Wii Sports type of games, or, as mentioned, swordfighting. The IR pointing function is one of the key elements in Wii Remote (what the Darwin is missing). If i understood Darwin correctly, it fails when player wants to change his/her position during gameplay (if some function is built around the positioning), while Wii Remote is built to register the change in players movements.

Well, i'd like to see the controller in funtion someday. I doubt it will really bring anything new and will be seen as Wii Remote ripoff.

Your position is calibrated, which has to be done every time you play and propably the initial geographic calibration is needed to be done also (atleast at the first time).