I wish I could remember where I read, but I know it was somewhere in the higher education discount site. Basically, if they audit you (which is completely random, though I suspect more often with online/phone orders... I went the noble approach and used my now 5 y/old college ID at the store and thankfully the guy still believed I was in college... though it wasn't much of a stretch) and find you're not an actual student, you're required to pay off the balance within 30 days or Steve Jobs will consume your flesh for repayment.
Ok, maybe I made that last part up. Still, if it were true I bet soooo many people would become cannibals.
EDIT: Ahh, here it is. Right on the Terms and Conditions.
Audit Rights
Apple routinely audits the purchases of customers at the Apple Store for Education to insure that only eligible purchases have ordered and that all purchase conditions have been observed. Should an audit disclose after delivery (or should Apple otherwise discover) that you were not an eligible purchaser at the time you placed your order or that you have not observed all of the conditions applicable to your purchase, you authorize Apple:
* If you placed your order by credit card, to charge to your credit card the difference between the amount you paid for the delivered goods and the price that Apple charged the general public for the same goods at the Apple Store, in effect on the date that you placed your order; and
* If you paid by a means other than credit card, to (a) invoice you for the difference between the amount that you paid for the delivered goods and the price that Apple charged the general public for the same goods at the Apple Store, payable in fifteen days from the date of the invoice, and (b), should you fail to pay the invoice when due, institute legal action against you in a court of competent jurisdiction, with the prevailing party entitled to attorneys' fees.
* Should Apple not offer to the general public the specific products that you purchased at the Apple Store for education, your credit card will be charged or you will be invoiced the difference between the amount you paid for the delivered goods and the price that Apple charged the general public for the closest equivalent goods at the Apple Store, in effect on the date that you placed your order.