My former colleagues at Info Support have it for some time now and sell it as part of their Endeavour offering.
I’ve implemented multiple variations, always with the help of the popular CruiseControl.Net
Microsoft has one named Visual Studio Team System
There used to be an initiative for an Open Source variant name NTeam but it appears to be dead.
Now apparantly the people at JetBrains (of IntelliJ IDEA and ReSharper fame) are building one as well. A Team Development System called TeamCity. From the webpages I conclude that they are implementing a distributed team environment which picks an available build server to run the next build on, and it will both build .Net and Java projects. Looks promising, I’ll keep an eye on it.