Thanks to one of our very own eagle eyed members kevpan815 we have spotted an interesting page on Microsoft.com regarding XP's support life cycle.
The page states General Availability Date of XP SP3 is 31/03/2008 meaning it may well have RTM'd already but the software giant has not made an official public announcement.
With rumours that Microsoft has delayed XP SP3 to encourage sales of Vista we'd hope to see Microsoft give an official response to this as soon as possible. We will update you once we get a response from the company.
Update: Microsoft has also posted a Windows XP Service Pack 3 Overview whitepaper.
Microsoft has confirmed that the final version of Windows XP SP3 is still on target to be released the first half of calendar year 2008 but has refused to confirm an RTM date.