has Microsoft released the official service pack 3 for windows xp?
or is it due?
Hasn't been released yet, and a preliminary release date of the first half of 2008. It will come out for sure - Microsoft have to keep support of Windows XP running for a few years yet (even if they stop selling it), and letting the Operating System become unsecure by not releasing periodic updates when its still "supported" could lead to lawsuits against Microsoft by big corporations.
A Vista Service Pack 1 will probably be released before the XP SP3.
Nope and since Vista came out I doubt they will.