This will be a a group of blogs dealing with what has changed in Windows 7
Windows AppLocker is a new feature in Windows® 7 and Windows Server® 2008 R2 that replaces the Software Restriction Policies feature. AppLocker contains new capabilities and extensions that reduce administrative overhead and help administrators control how users can access and use files, such as .exe files, scripts, Windows Installer files (.msi and .msp files), and DLLs.
AppLocker rules specify which files are allowed to run. Files that are not included in rules are not allowed to run.
A interesting feature of Applocker is that you can say allow application x and all new versions so that you can allow users to get upgrade without having to recreate new rules.