[Thank The Cheese]

you can't do it yet, at least not in the same way you can with DVDs. Your best bet is to use the analogue hole. If you have something that can get HD signals into your computer, like an EyeTV or some kind of AV receiver box, you might be able to do it that way.

for example, buy a standalone BluRay player and start playing the movie, then go from HDMI or Component out from the player, to an HDMI or component input on the AV box. Then go from the AV box to your Mac, which is capturing and recording the program. You're going to lose quality, but I think it's the only way at this point in time.

They have tried to plug the analogue hole too by encrypting the HDMI connection, but as far as I know they haven't started enforcing that, mostly because a great number of HDTVs don't yet support the HDCP spec.