Windows XP SP2 beta will be downloadable from MSDN?
According to a C|Net article the incoming beta of Windows XP SP2 will be available soon also on the MSDN web site.
Perhaps all the security improvements (Firewall turned on by default, Windows Messenger Service turned off by default, new security models for IE and for the newest processors, etc...) will require a deeper test than the previous SP.
Start your engines...
[Source: Winbeta]