This avoids the need to install Visual Studio on the build server.
I have just tried this out now, and can verify that it works:
error MSB4019: The imported project "C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\WebApplications\Microsoft.WebApplication.targets" was not found. Confirm that the path in the declaration is correct, and that the file exists on disk.
After the install:
This is a far better solution than installing Visual Studio on a build server, obviously.