We probably don't pay enough attention to the GNU projects, but Rllmuk brought it to my attention that a team are cheerily developing from the now-openly-sourceable remains of one the great lost RTS games of the nineties: Warzone 2100.
The current version, 2.0.8, seems to include operative campaign and multiplayer (though the next release, which has been delayed from December into early 2008 promises full online compatibility between all its supported formats). Returning to the game after so long away brings back a fair few memories - as far as I'm concerned, it was the first real 3D RTS and its lack of sales success a complete mystery. In fact, its novelty in those areas may even be part of its failure - people were bewildered by the 3D power being thrown around, as well as its novel (pre-Earth 2150) unit-assembling functionality. In fact, its ever-expanding maps look even more prescient in world of Supreme Commander. Still worth playing and probably the greatest game to ever come from the City of Bath. Except, possibly, Zeewolf.