MS has made upgrade versions the equivalent to the former 'Retail' version, if you have a Windows 7 OEM OS you can upgrade it with a W8 upgrade. Then you have a W8 OS with the equivalent of a 'Retail' license and are allowed to move it to another computer.
The Win8 System Builder license has become a dual-purpose one. For a DIY user, it acts similarly to the old Win7 full retail license. It is transferrable to new machines indefinitely, by the original owner.
If the license is transferred to another person, it functions like the previous Win7 System Builder license, with the usual OEM restrictions. (Not transferrable to a different PC.)
I've never seen anything that a Win8 upgrade license is transformed into the equivalent of the old full retail license by having been used to perform an upgrade. That's what the current "discussion" boils down to. I'd like that to be true, but I think that it's not what Microsoft requires. (On the other hand, the current Win8 pricing is nonsense. $140 for Win8 Pro System Builder, $200 for Win8 Pro Upgrade. Crazy.)
