Support for Windows XP and Windows Vista has seemingly been dropped from Boot Camp in Mac OS X 10.6.6.
A report on the MacNN website notes that when creating a Windows partition using Boot Camp you are now asked for an "authentic installation disc of Windows 7 Home Premium, Professional or Ultimate", with no mention of Windows XP, released in August 2001, and Windows Vista which debuted in January 2007.
Boot Camp also requires the user to download Windows support software designed specifically for each Mac. This driver bundle covers everything you need for peripherals such as keyboards and printers and is installed in preference to software from a Mac OS X install disc to ensure each system has the latest drivers.
Boot Camp 3.2, released in November last year, did support Windows XP and Vista as well as being compatible with 32-bit and 64-bit versions of Windows.
The MacBook Air, though, only supports Windows 7, but the Apple website makes no mention of any other lack of support for Windows XP or Windows Vista.
Mac OS X 10.6.6 brought a number of updates, most significantly the Mac App Store, when it was issued in early January.