They used to. I don't know how much of a discount it was. When I bought my MBP, the guy said I could use the student discount once a year. When I asked him to clarify, he said I could buy one computer, iPod, software pack, and whatever else had a discount on the discount each year.
Apple has gotten pretty bad about the so-called student discounts. For example, a new OS was $69 on student discount when the regular price is $129. Now the discount is only like $15. I got a better discount just buying straight off Amazon with no special discounts! Also, $8 off software packs like iLife and iWork? That's actually kind of insulting.
I think Apple needs to follow Microsoft's example. They should offer huge discounts to Universities and students. It will be a loss now, but it's all about getting people using your software as soon as possible and reaping huge profits in the future. Once someone gets set in their ways it hard to change, especially with something as complex as a computer.