There are ways, and they do check. Randomly. How do I know? Because I've been checked. Twice, actually.
Once, when I ordered my maxed out 15" PB, and again when I ordered an iPod Shuffle.
I received a call from Apple asking for proof of enrollment. They provided a fax number and asked that I either fax a copy of my tuition bill for the current semester, or a copy of my student ID.
I've also known a few people who were checked when all they bought was a cheap media card reader. Apple does check, and defrauding them will only cause problems for the legitimate users of this program.
That's funny because I had a friend who was buying a new iMac for his wife.
The guy in the store asked if either of them were teachers. They are not.
Then he asked if they were planning on taking any classes at a university or going back to school. They are not.
Then he said, well do you have any kids? They have a son.
He said, well, do you ever plan on using the computer to teach him anything? Before they could answer, he said, "Eh, I'm sure you will. I'll give you the education discount."
Regardless, you can get a refurb and save more than the student discount anyway and not worry about scamming Apple.