There's now an OS X firmware upgrade program available for the Pioneer DVR-104, -105, -106, and -107, which means it's possible to fix your drive without taking it out and putting it in a PC. Thanks to xvi and friends, I can now watch Japanese DVDs on my G5 without worrying about running out of region code changes. (In case anyone hasn't needed to do this before, you'll also need Region X from xvi's page.)