It uses SD cards. They're available up to 2gb, which is the largest size this camera can use. Be careful not to get SDHC (high capacity) cards, as they will NOT work, even in the 2gb size.
I've used 512mb and 2gb SD cards, both PNY brand, with success. They aren't fancy high speed cards, but I don't notice any objectionable delay in writing to the card.