Microsoft announced Mainstream Support for the Windows XP operating system will end on April 14, 2009. The operating system will move into Extended Support until April 9, 2014, until that day Microsoft will continue to provide security relevant support for the aging operating system.
The end of the "Mainstream Support” for Windows XP means that from this day on new updates will not be available for the operating system. The same applies to hotfixes that aren't part of the common update program - up to now they could be requested from the Microsoft support. So another Service Pack for Windows XP with new features is most unlikely to be offered.
Windows XP will still be supplied with security relevant updates for free - at least until the scheduled end of the "Extended Support” on April 9, 2014. Part of this support are windows XP Professional, Windows XP Home Edition and Windows XP Media Center Edition.