A marketing campaign by Microsoft to show that Windows is the only PC gaming platform(Mac OS has very few games and Linux has no hope of being a gaming platform). Games showing this are expected to be Windows Vista compatible. The new GfW DVD case is designed to be similar to conole game cases.
Windows user: Games for Windows - that gets to the point. Sucks to be a Mac.
Mac user: DAMMIT MAN! Where are all the Mac games.