Way back in like 2003 we sent several e-mails to Lucasarts about using some of the material from Galactic Battlegrounds for a Civ3 mod and they never gave a response back. More recently, Lucas himself has been open about people using stuff from Star Wars for fan-films and games as long as you don't profit from it. I'm assuming it is ok.
BTW, I do give credit to LucasArts and Galactic Battlegrounds for the units I've made from that game.