This is a rather dumb question, and I apologize in advance, but with a P2 card in the HVX, can you transfer the contents of the P2 card to your computer using the firewire out on the camcorder like how you would transfer tape footage?

Yep, I'm an idiot. I found my answer in Panasonic's FAQ. I can't wait to get my P2 cards.

You can do it both ways: you can play the footage using playback, and "capture" the firewire stream, or you can choose to view the card as an external hard disk and just copy the files over. Copying can be a lot faster than capturing, of course.