Besides releasing version 5 of Microsoft Application Virtualization (App-V) yesterday, Microsoft also released Service Pack 2 for App-V version 4.6.
Service Pack 2 provides support for Windows 8 and Windows Server 2012, but more important allows for coexistence of the 4.6 client together with the App-V 5 client so that the 4.6 App-V packages can work side-by-side with the new 5 APPV packages.
Besides that SP2 also contains a rollup of all hotfixes released after Service Pack 1, which was released in March this year.