It is a shame that Battlefront isn't currently available for Mac, but I recently tried an extremely well done mod for UT 2004 called UT 2004 Troopers.
Back when I was writing for the games industry I covered the beta version for Modsquad, but its come quite a long way, featuring the beauty of the UT 2004 engine with authentic rebel vs. imperial action. Recently, tie-fighters, x-wings and even speeder bikes (which i actually prefer to the ones found in Battlefront) where added. It has a very tight-well integrated feel that seems better put together than Battlefront.
Sadly, not many servers are active right now. I also believe that there's a compatability issue with the latest UT 2004 mac patch and most recent version of UT 2004. It'll most likely be addressed soon though - definitely a must see for star-wars/mac users.