Right, and XP was just an enhancement to 2000, every version of OSX since the initial release is just an enhancement, and every version of Ubuntu ever is just an enhancement (every 6 months baby!) The correct answer was "probably because it's an incremental kernel upgrade, not a new kernel"
It's officially Windows 6.1, not Windows 7.
Also, let me know when linux kernel 3.0 comes out - but 2.6 vs. 2.4 is a hell of a lot different.
Wait, which point am I arguing?