Responding to Enterprise and business customer concerns, Microsoft is now going to be extending the life of Windows XP into 2011. The previous life extension took it into 2010 (6 months after the expected release of Windows 7), but it now looks like there will be an 18 month window for Windows 7 Professional and Ultimate customers who may used to downgrade to Windows XP. Unless Windows 7 SP1 comes out before that. Microsoft announced that 18 months or the delivery of SP1 whichever comes first.
According to this Computer World article this latest XP life extension came about after a Gartner analyst, Michael Sliver took Microsoft to task over the previous 6 month time frame.