Vista, MSBuild
One nice thing about Vista is that it includes MSBuild out of the box.
The .NET Framework comes with a compiler (and has since 1.0), but didn't come with any build tools, so even if you included source code, you'd still need to include something (or tell users where to get something ) to build your code.
Now you can include the same project and solution files that Visual Studio uses, and users can simply unzip, msbuild, and run.
Nothing new for the Unix folks but for Windows, this is a first.