In their own words:

Project Description
This is a service based system with a front-end allowing the dynamic addition of event handlers for Team System. Users can upload their own custom Handlers as part of an assembly which are then loaded and executed on the server. This application runs in conjunction with TFS (Team Foundation Server) and handles all of the events that are generated by the server.

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Contributors

Very cool!  This project should let you build things like "automatic branching on work item change" into a custom TFS workflow. 

Hopefully project managers will use this tool for good (automating repetitive processes) rather than evil (adding extra management overhead just to justify their job).  I kid, of course -- all PMs are good, right?  I think I'm still smarting from being called one.  Just stay away from automatic merging and you'll be ok :)

PS thanks for the waffles