Made the leap today: I wiped OS X off the hard drive on my MacBook and put a fresh, clean install of the newest version of Ubuntu (7.10, or ‘Gutsy Gibbon’) on it.
Everything worked out of the box save for wifi, and there’s a workaround for that. 7.10 looks great, the MacBook feels more responsive, and getting/installing software is easier than in OS X. No Leopard for me. I’ll stick with the penguin.