Wait, why did we not post here about this yet?
http://spaceempires.net/forum-105.html
Combat Wombat and I, as well as one of Combat Wombat's real-life friends, are working on an open-source clone of SE4 called FrEee. (Ha ha, get it, free the Eee :P)
So far we have most of the main game screen laid out, as well as a few subscreens and barebones turn processing, so you can build facilities on your homeworld, and that's about it. Probably sometime in the next few days we'll release a binary for folks to play around with, not that there's actually anything interesting to do in the game, but just to get some feedback!