RAM is customer upgradeable, you can send it in when you get a repair ... never had any problems with that.
My apple repair lady actually recently told me that in her many years of repairs, RAM is not usually the problem for anything, but APPLE likes to tell everyone it is, because they don't want it to be their fault ... makes enough sense to me.
"For AppleCare owners: Your computer must retain at least ONE stick of Apple-branded RAM to continue to qualify with AppleCare. For 12" PowerBook and iBook owners, the logic board RAM satisfies this requirement. For all other computers the Apple-provided RAM must stay with the computer until AppleCare expires."
I'm glad I saw that. When I get my macbook (stock), I'll be putting my own in. I'll be sure to keep the stock Apple ram though, so I can put it back in if I ever do need to send it in.