So today I had the enjoyment of the infrastructure team changing the workstation station naming conventions company wide. Which if you have been a developer for sometime this usually will make you cringe.
With Visual Studio Microsoft included a command line utility tf.exe which is usually located in *\Common7\IDE. This utility allows you to do more administrative style commands that are hidden from the UI side of visual studio.
To updated the computer name for all of your workspaces in a collection you would run something like this:
tf workspaces /updateComputerName:oldcomputername /collection:http://tfsServer:8080/tfs/DefaultCollection
If you are going across domain you might need to send the /login:NetworkName with it.