A week ago we reported that Microsoft will publish Windows XP SP3 today. The plans have changed a bit as it seems.

MSDN subscribers have already been able to download Windows XP SP3 for a couple of days. A download to none MSDN members could be expected next week, if I interpret this post from Microsoft's Chris Keroack correctly.
Update 04/30/08:
XP SP3 web release delayed


Update: It seems a direct link to the XP SP3 download link at Windowsupdate has leaked. I am not totally sure that this is the right file, so I am not downloading it. More details on that link on Dailytech.

Windows XP Service Pack 3 (SP3) includes all previously released updates for the operating system. This update also includes a small number of new functionalities, which do not significantly change customers’ experience with the operating system. This white paper summarizes what is new in Windows XP SP3.
Some test reports still say that there is a performance increase of about 10% with SP3. See this XP SP3 test report on InfoWorld for instance.