I've done it with friends on numerous occasions, both online and in-store (for computers and accessories), and I may be using the HED discount within the next two weeks (right now, Amazon.com is actually cheaper because they won't charge me sales tax, Apple will, and they'll give me a $100 mail-in-rebate that'll leave me back at the pre-tax price the education discount offers), but in the store, it can vary clerk to clerk, but if you show them a student ID or an acceptance letter (or even a transcript or certificate of admission form), you're fine. Online, the only time I've ever seen the checks are when software purchases are involved. This actually makes sense. I've been buying academic software since I was in high school (I'm 24 and in grad school now) and have always had to fax proof of registration and some sort of photo ID, regardless of the place of purchase. The way Academic Software works is that the software companies get a write-off, essentially, for offering educational discounts (why else do you think Microsoft started selling the Student versions of Office in retail stores -- where NO one cares to make sure you really *are* a student -- they get to write it off and probably save a sale from piracy) -- so there has to be official documentation associated with that discount, proving the buyer was a student (Microsoft gets around this in the retail sector by basically putting a "disclaimer" on the box that you are only to use the product for academic or home purposes or whatever...but again, the Academic POS thing is more of a piracy prevention tool than anything...you can get academic copies of more advanced versions of Office (if we're talking about Windows, not 100% on what the Mac options are, though if they have different configurations, I'm sure it would work the same way) for the same price or less if you go directly through an authorized academic reseller than the standard version anyway). Hardware discounts are more of a good faith thing on behalf of the company (which is why IBM, HPSHopping and Dell all have student discounts too), they aren't getting a write-off for it -- it's just a ploy to get students or educators to shop with Apple or whoever directly, and use the incentive of a small discount to get a sale they might otherwise lose.
That was long and drawn out - sorry, point being -- in a store, they'll want an ID or acceptance letter, but it's not a huge deal -- you could use fake letterhead and it would work (I'm not suggesting that -- just saying, it wouldn't matter), but if you are getting academic software online (or in store, if they happen to carry the academic version), yeah, they're going to want verification details so they can get their write-off.
That was long and drawn out - sorry, point being -- in a store, they'll want an ID or acceptance letter, but it's not a huge deal -- you could use fake letterhead and it would work (I'm not suggesting that -- just saying, it wouldn't matter), but if you are getting academic software online (or in store, if they happen to carry the academic version), yeah, they're going to want verification details so they can get their write-off.