It doesn't support BD-J yet (on going)
That's very good news. If VLC manages to get full Bluray support, mac users are really going to open champagne bottles (even if it's for unencrypted Blurays only).
Now, If you want to play a bluray on a mac, besides the fact you have to manually copy the encrypted disc to an HDD with some program, there is no player for OS X that supports BD-J, so you are essentially losing all the menus. Same applies on Linux.
Is there any site documenting the progress done on BD-J? What is done, what is left to be done etc....