Chris Jackson has a great article on the reasons behind why Windows Installer 5 (Windows 7) custom actions are lied to by the shimming engine. It also provides another great example that Microsoft is committed to the shimming infrastructure to the point where major segments of the OS rely on it for their own compatibility. Shimming is not a bolt-on!

Why Custom Actions get a Windows Vista Version Lie on Windows 7

Topic: Application Management, Win7 / Vista, Windows Installer