the machine itself is actually capable of handling up to 4GB of RAM, which is obviously never going to happen. i think it would be years before we see an affordable 4GB RAM module for a laptop. anyway, there are 1GB chips already available but they cost around $1000, the cost of a new iBook, or about 20 lap dances ath the nudie bar, if that's your thing. so yeah, for the average joe 640 is still the realistic limit but i'm sure there is some guy with money to burn who has a 1GB chip in his 12" PowerBook. the bastard.