AppLocker is a feature available to administrators of Windows 7 Ultimate and Enterprise (Software Assurance) editions only. It allows administrators to use group policy to define what applications can be run on Ultimate and Enterprise computers. Obviously these policies won’t work on Vista or the other editions of Windows 7, e.g. Business.
Microsoft has released some technical documentation on the feature:
“The AppLocker Technical Documentation for Windows 7 and Windows Server 2008 R2 provides technical guidance about understanding how AppLocker works and how to effectively plan and deploy AppLocker policies.
AppLocker in Microsoft Windows Server 2008 R2, Windows 7 Ultimate, and Windows 7 Enterprise helps administrators control which applications are allowed to run in their organizations. These documents provide technical guidance about understanding how AppLocker works and how to effectively plan and deploy AppLocker policies”.