Looks like the good folks over on the MDOP blog just announced the immediate availability of Microsoft App-V 4.5 SP2:
App-V 4.5 Service Pack 2 provides the latest updates to Microsoft Application Virtualization 4.5 code line. This is the first time the team has delivered via Windows Update App-V 4.5 SP2 introduces:
To learn more you can get all the details straight from the source.
J.C. Hornbeck | System Center Knowledge Engineer