The big thing that seems to have changed is that companies are now selling OEM System Builder products with no hardware requirement. Previously, in order to acquire OEM System Builder versions, you could only purchase sealed three-pack or 30-pack System Builder SKUs without a hardware requirement. These sealed multi-packs could not be opened and the individual OS packs therein sold or transferred without a hardware requirement, but the purchaser of those multi-packs could install them on his own computer(s) (which would satisfy the hardware requirement for subsequent transfer or sale by tying the OS license to a machine).
Then about two or three years ago, everyone started selling OEM System Builder products in single packs with no hardware requirement, including major retailers (not just the smaller PC shops or businesses who historically were the source of separated or "diverted" OEM System Builder products without a hardware requirement in violation of MS rules), now with Microsoft's apparent blessing.
The official position expressed in writing through MS OEM System Builder Channel was that System Builder products could be acquired and used by DIY/BIY purchasers for their own computers, as long as they acquired the product in compliance with MS rules on distribution or transfer (sealed multi-packs without hardware requirement, or individual packs with hardware requirement), and further complied with the System Builder Licensing Terms or Agreement on the major points of providing support and not transferring the license from one machine to another.
I would have saved screen shots of those FAQ pages on the MS OEM Partner website had I known MS was going to try to deny this was ever its position/policy. I'm still not convinced MS is attempting to do so, just because Ed Bott says they are.