Now on Steam and in the App Store
Aspyr, the company that ported Jedi Academy to OS X, has re-released it. Previously, playing Jedi Academy on OS X was notoriously difficult: though it worked on older versions of Apple's operating system, newer versions like Mountain Lion required various workarounds, and sometimes did not work at all.
Update: Apparently, there are still some issues with this re-release. If you do not have all files the server you are connecting to has (which is often the case), you will receive an error, and be unable to play on that server. Hopefully, Aspyr will fix that soon.
Update: Due to the issues with this re-release, I highly recommend not using this version yet, until they're resolved.