When many organizations move to Windows 7, they also take on the task of discovering, inventorying, testing, and remediating all of their current applications currently used in production. Often part of that process includes a decision to deliver those applications with App-V. The App-V 4.6 SP1 Sequencer and client offers a streamlined workflow to virtualize, package, and deliver those applications to the desktop or RDS server providing a simplified, centralized approach to application delivery and management. It also, at the same time, resolves many application interference issues through isolation and state separation.

When a product such as App-V undergoes a significant maintenance release, there are always the possible regressions. With 4.6 SP1, there were a few, and the App-V team was able to quickly isolate many of them and provide fixes in a timely manner. Servicing is always an important process in the support of production software.

App-V service releases (a.k.a hotfixes) are released in a manner that allows for the simplification of the deployment of fixes. Hotfixes are based on major release points (i.e 4.6, 4.6 SP1) and are designed to be cumulative. This way, if you deploy the recent hotfix pack, you can rest assured you are getting all of the cumulative patches released since the last major revision. In the case of App-V 4.6 SP1, the most recent release is 4.6 Hotfix Package 6 (build 4.6.1.30121.) if you are not currently running your 4.6 clients at this build you can leverage the hotfix download link found with the associated KB article here:
http://support.microsoft.com/kb/2693779

The hotfix packages are made available in MSP format. This allows for flexibility in enterprise deployment of the patch.  Remember, since the patches often affect revision changes of the App-V filter drivers, a reboot is necessary when deploying the patch.

But What about the Sequencer?

As many client changes involve patching the App-V System Guard (the component that facilitates the virtualization engine) it requires making revision to the App-V 4.6 SP Sequencer as well. I always advise all of my customers to ensure that they are always using the most recently released build of the App-V Sequencer.
The relase process for the sequencer is slightly different. Not every cumulative patch, involves a change to the sequencer. With this, you will not always see inclusion of the sequencer with every cumulative hotfix release. In the case of the most recent release of App-V as of this writing, the most recent service release of the App-V 4.6 SP1 sequencer is the refresh build that came with 4. SP1 Hotfix 3. You can download the release via the KB article for the hotfix here:

Hotfix Package 3 for Microsoft Application Virtualization 4.6 SP1: August 2011
http://support.microsoft.com/kb/2571168

Instead of an MSP file, when a sequencer is patched, an entirely new installation is made available. This makes sense because sequencer machines are often never “upgraded.” They are often cleanly reverted. This allows sequencing engineers to refresh their machines images used for sequencing in a clean manner without having to worry about patching.