The update will come in the form of a new patch for the client (called Trinity), which will also feature new ingame ships, lots of new items, and updated graphics textures. I've only just recently gotten into EVE Online, but it's a good time for a space-based MMO-- really complex economy, harsh PvP, and excellent skill system. I know some Mac users have already been playing it with Boot Camp and Parallels, but it'll be nice to finally have a native Mac client.
The patch is supposed to drop next Tuesday, so the Mac client should be available on the site sometime soon after that. Get ready to head into low sec space on your Mac, but be careful-- the rats are out in force.