If the following attached image is REAL (not my own) then I understand that
Windows XP Service Pack 2 RTM Build 2180 is the Final Build.
The file name is WindowsXP-KB835935-SP2-ENU.exe
Note that
WindowsBeta
http://windowsbeta.microsoft.com/
is an OFFICIAL MS beta testers site for members only
I tried it and it FAILED with "Server Too Busy"

hehe
which would indicate that they are downloading it like crazy
I for one will be waiting for an OFFICIAL "public" download link from
download.microsoft.com and will sit it out a while (letting others be guinea pigs) before I even think about using it.
Note that the release notes are "public" at:
Release notes for Windows XP Service Pack 2
http://support.microsoft.com/?kbid=835935
Last Reviewed: 8/6/2004 (5.0)
but there is no "public" network install download link (yet).