Installing MSBuild 4.0 without Visual Studio 2010
Perhaps this is the SDK disguised slightly as a Windows 7 SDK.
Microsoft Windows SDK for Windows 7 and .NET Framework 4
UPDATE: Based off of a blog posts on the Windows SDK Blog the SDK that I linked to above seems to contain msbuild and supports building managed (.NET) applications. I'm assuming this is the SDK we have all been looking for in order to install on our build servers so I'm downloading it now and I'll post any further findings after I check it out.
UPDATE: I can confirm that the link provided above does indeed install MSBuild along with other portions of what would constitute an SDK for .NET 4.0. I'm successfully using this on my build machine now without installing Visual Studio 2010 to build our project.
UPDATE: Please also see FrederikB's answer below as it appears that the whole SDK may not be required to get MSBuild 4.0. This would be especially useful if you need to set up a minimal build server. I haven't confirmed whether this works for me or not but it would be worth a try before installing the SDK.
UPDATE (Feb 2022): Most recently when I needed to work with msbuild for an older .NET Framework project I was able to do so using the Build Tools for Visual Studio. The most recent version at the time of this update can be found at the Download page for Visual Studio itself. Look for Build Tools for Visual Studio 2022 under the section labeled Tools for Visual Studio 2022. Obviously the modern equivalent in the age of .NET 6 is to use the universal .NET SDK which includes the dotnet
cli tool as a big improvement over MSBuild and in some cases can still be used to build certain .NET Framework projects.
If you're looking for msbuild, you'll find that for 4.0 it's at:
For 32-bit:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe
For 64-bit:
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe