Version 184.108.40.206 of the MSBuild Extension Pack has recently been released!
This release of the project includes my DynamicExecute class (online docs), which allows build masters to include C# code right in their MSBuild scripts. This code is compiled and executed at build time, which provides a whole new level of MSBuild extensibility.
If you’ve ever found yourself frustrated by the lack of MSBuild usability, this should come as a real relief. :)