Ran into a small stumbling block today on the Network. 
I had a user request to have an Add-In Disabled on the workstation.    No problem easily done.
Go to list of Add-ins and just "Clear the Box".
But I thought for a moment, I like being Laz….. I mean "Centrally Efficient" and controlling as much as possible from Group Policy.  Oddly enough (And maybe I’m missing it) I couldn’t find a GPO to control Addins at all.   Either to deploy, or more importantly, to disable.
But if you’re running Server 2008 with a newer Domain?  You’ve get a GREAT Feature called Group Policy Preference Client Side Extensions you can leverage.  And it will work on Windows XP, Vista, Server 2003 and Windows 7 as long as you have the Group Policy Preference Client Side Extensions Hotfix installed on the workstation.
For Windows XP          – Download Here
For Windows XP x64    – Download Here
For Windows Vista       – Download Here
For Windows Vista x64 – Download Here
For Server 2003           – Download Here
For Windows 7            – Built right in!
So if you have a Server 2008 Environment with the newer Group Policy there is an addition option now called "Preferences".  These DON’T Negate the regular Group Policy options.   Think of them at what they are, Extensions.   Do GPO’s the normal way but there’s a whole new way of tweaking very specific features like drive Mappings etc.
Or today, applying Registry settings!
So in my case I had to Disable the Office Live Addin.  Nothing wrong with it, but we just don’t need it in our environment.   So we’d like it disabled.  
So under HKEY-LOCAL-MACHINESoftwareMicrosoftOffice there are a series of keys for Word / Excel / Outlook etc. ( If you’re on a 64bit workstation the actual location is HKEY-LOCAL-MACHINESoftwareWow6432NodeMicrosoftOffice )
Under each entry you will see "Add ins" with a Subkey for each Add in, like this
The Value to note here for each key is called "Load Behaviour".  If it has a value of ‘3’ it will run the add-in automatically, if it has a value of ‘2’ it is "Disabled" although still present in the file system.  I like disabling rather than uninstalling, far easier to "Flip the switch on" if needed.
And you can probably even use a script to do this do.  But with Group Policy Preference Client Side Extensions, I can push that Registry change to my workstations centrally.
I just go to the Computer Configuration in Server 2008 GPO, Pop into the Preferences for there and you’ll see an Entry that says "Registry"
Just Right Click on Registry, Choose "NEW, the Registry Item" and fill out the forms as appropriate.
You can even browse to the key but for now we’ll type the details in directly.
Path is "SoftwareMicrosoftOfficeWordAddinsOLConnectorAddin.Connect" (That’s the Key we’re modifying)
Value Name is "LoadBehaviour" (since that’s the value we’re changing)
Value Type is "REG-DWORD" (since that is the original value type, you can tell by viewing with REGEDIT)
Value Data is "2" (Normally for Addins it’s ‘3‘ which is enabled, ‘2‘ is disabled, I found this out by changing the settings and looking at values after)
This will disable the Office Live Com Addin in Word.   If you need to do this for Excel?  Just change the Path to "SoftwareMicrosoftOfficeExcelAddinsOLConnectorAddin.Connect"
Also note, if you’re working on a 64bit machine, and since Office is a 32bit app, it’s path will be "SOFTWAREWow6432NodeMicrosoftOfficeWordAddinsOLConnectorAddin.Connect"
But you CAN control all these addins from Group Policy thanks to Group Policy Preference Client Side Extensions.   It takes a tiny bit of thought, but it’s worth the effort since you can now manage all of this for anything from 5 to 50,0000 workstations EASILY!
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