Apparently, the SVN revision is different on SU than on SO/SF/meta. At the moment it's 3970 on the former and 3966 on the rest. This must mean that you guys don't really have an automated deployment process that builds the source in one click and deploys it automatically to all sites. The kind of one click deployment one Joel talks about all the time.
Or is it just that you have only deployed SU manually because it is beta?