Sets the name of the build. For Tfs 2005 use $(BuildType), for Tfs 2008 use $(BuildDefinition)
Namespace:
MSBuild.ExtensionPack.VisualStudioAssembly: MSBuild.ExtensionPack (in MSBuild.ExtensionPack.dll) Version: 3.5.0.0 (3.5.4.0)