I thought this was a pretty interesting concept. Looks like Naturalpoint is branching it's TrackIR use from flight and driving sims into the FPS's. This looks like it's first implementation of it. The game is Armed Assault (not released yet), a remake/clean-up job of the original Operation Flashpoint, and a stepping stone to OFP2. Pretty neat idea, though I'm sure it would take some getting used to.
http://www.armedassault.org/web2/downloads/pafiledb.php?action=file&id=5