If you are trying the new Visual Studio 2012 TFS Git source control and are trying to pull from master and get the error that "There are changes in the current working directory." You should add the ".gitignore" file the following:
".gitattributes" and ".gitignore".
Feb 26, 2013 Update -- Apparently my ignorance caught up with me. You should not ignore the .gitattributes file, but add it to your repository from within Visual Studio. (Thanks Eric).