Microsoft said Monday that it has expanded its testing of Windows XP Service Pack 3, to include subscribers of its MSDN and TechNet programs. Last month, Microsoft made available a test version of XP Service Pack 3 to a group of about 15,000 testers. The update is significant in that it is the largest change in some time to Microsoft's most-used operating system. However, the XP update is largely a collection of previously issued bug fixes and security updates.
A public beta is scheduled for some later date, with a goal of having it released in final form in the first half of next year. However, Microsoft cautioned that its "timing will always be based on customer feedback as a first priority." Anticipation over the timing and features of the release has been going on for years. XP SP3 was initially expected as early as 2006, but was delayed as Vista work remained the priority for the Windows team. The first service pack for Windows Vista is also due out in the first half of next year.
Source: CNET