The hack depended on a leaked bulk OEM licence, which installs on an unlimited number of PCs, assuming they match the assigned hardware certificate. Traditionally, once these cracks are out the the bag they're, well, out of the bag—any measures that could take down pirated copies would also disable installations that used the key legitimately, leaving Microsoft with their hands tied.
Seeing as Windows 7 isn't even out yet, this particular master key hasn't been used for any software that's actually shipped yet, so Microsoft is free to blacklist to their heart's content, which they have. Don't fret, sad thieves: this doesn't necessarily mean that a future key with some useful collateral couldn't accomplish the same thing, someday. [Ars Technica]