Correct. You need an APPLE ID, not (necessarily) a .Mac account. Get an Apple ID just by signing in for the first time and filling out the virtual paper work.
BTW, I'm addicted to the iPhoto print service. It's sharp. I've done books, calendars, birthday & Christmas cards.... way too much. I ALWAYS get compliments on them.
Except last year when most of my family threw the cards away after Christmas thinking they were just regular store bought cards like everybody else's. When I told them I made them myself from pictures I shot, they were shocked.