Hidden work arounds and complex dependencies

"While chief technology officer Ray Ozzie was away in the clouds at Microsoft's Professional Developer Conference, technical fellow Mark Russinovich got down and dirty with the true heart of Windows - the kernel.

He presented a two-hour session on changes made to the kernel used by both Windows 7 and Server 2008 R2, shedding light on some confusing issues - like the Windows version number, which he said "means nothing at all". Windows 7 is version 6.1, not because it is a minor release, but for compatibility with applications that check the major number and would not run if it said 7."...The Register

Mark Russinovch - Inside Windows 7 Redux