Sorry for the double post, but HOLY COW!
I'm at work, on a PC with none of my home contacts. I went to my .mac account to "turn on" the syncing in the .mac address book, and when I did, it said syncing now.
Somehow, all of the contacts from my home computer are now on my .mac address book!
It synced with my home computer... Either the info was already in my account and just updated into .mac or I can sync with a computer that I'm not at!
This is so cool!