A very interesting development that I picked up thanks to LGDB is the Open Imperium Galactica project.
Another open source clone of a proprietary game, Open-IG doesn't require external datafiles to be played; it comes with a launcher which downloads all necessary files for you. It has a rather wide variety of gameplay, from 4x galaxy management, to city-building, to rts battles in space and on land. A very cool game and definitely a project to watch.