Windows 32bit Family XP RTM - 5.1.2600
XP SP1a - 1106
XP SP2 - 2180
Server 2003 RTM - 5.2.3790
Server 2003 SP1 - 1830
Server 2003 SP2 - 3959
Vista RTM - 6000.16386
Server 2008 Beta 3 - 6001.16510
Windows 64bit Family XP 64bit RTM - 5.2.3790.1830
XP 64bit SP2 - 3959
Server 2003 64bit RTM - 5.2.3790.1830
Server 2003 64bit SP2 - 3959
Vista 64bit RTM - 6000.16386
Server 2008 64bit Beta 3 - 6001.16510
As Mary Jo Foley forecasted, a Windows Vista SP1 drop was made in mid-July. We're hearing, however, the drop was made to a small group of random testers for "pre-beta" testing. Pre-beta testing is usually conducted to test software that is more mature than a first-stab, annihilate-your-machine alpha but doesn't quite implement all the required functionalities to be labeled a true beta.
The service pack comes labeled with a build string matching its recently released WDK brother and smells of Server 2008 kernel, which is A Good Thing™ -- 6001.16549(longhorn_sp1beta1.070628-1825). (Thanks C.)
Queried Microsoft and beta participants are denying the program's existence, as expected. We'll have to suffer with our malfunctioning Windows Vista installs for just a tad longer.