hi,
i am going to uni this year, got an email the other day saying that i can get a 15% discount on a new Mac, £122 rebate on an ipod, £70 rebate on a printer and £57 applecare.
Spoke to the guys in store about this yesterday and on the phone today. It seems to be 12-14% depending on your college or what you buy; difficult to get a definitive answer.
If you're in the UK and join the NUS their website says you can get up to 15% discount. Haven't tried that yet.