I have just posted an article about scheduling multiple builds with Team Build and MSBuild at my Telerik blog. Here is an excerpt:
If you are working on a large project it is very probable that the project is composed of several parts/modules which are build separately. What are your options if you want to be able to rebuild the whole thing easily? If you are a Quake tournament winner equipped with Razer Copperhead mouse you could probably schedule 10 builds (in the right order) in a matter of seconds but what about your colleagues that are not so gifted? Well, there is the TfsBuild command line tool but in case you are using the 2008 version and you would like to have the freedom to choose a build agent when scheduling a build you are out of luck. It seems that the only viable option is to write a custom tool that talks directly to Team Build.
You can find the whole blog post here.