The question whether you can force that Code Reviews must be done before checking in a set of changes in TFS. And up until recently there wasn't. Colin created a check-in policy and shared it on the Visual Studio Gallery.

It will show up like this:

Grab it while it's hot it this is something you really want/need. I'll personally not be using it, since I currently have a co-located team with excellent communication going on at the moment.