One of the nicest features of Team Foundation Server are the check-in policies. They allow you to validate specific rules before each check-in. What makes this even nicer is that you can easily write your own check-in policies. However there is one problem, the check-in policy(read: DLL) needs to be installed on the developer machine. This is important because if developers do not install check-in policies they would not be run during a Check-in.
Before you start inventing the most complex deployment strategies to get the latest version of these policies on the developer machines, note that there is already a feature available, included in the TFS power tools.
After installing power tools, a new node is added in Team Explorer called Team Members. Right click in the Team Members node and choose Personal Settings.
From there you can see all the options for the collaboration features and one interesting option called Install downloaded custom components.
This extension verifies in the source control the presence of a path called $projectname/TeamProjectConfig/CheckinPolicies and inside that folder looks for 1.0 2.0 or 3.0 folders for VS2005 VS2008 and VS2010 addins respectively. Every dll found on that directory is automatically downloaded to the right location and made available to client computers.
Remark: You can also include dll’s containing custom controls for work item editing, they should be included in a folder called $projectname/TeamProjectConfig/CustomControls.