I moved everything from one TFS server to another TFS server, and I decommissioned the old TFS server. I had some old workspaces from an old Team Build account, and they had left some items with pending changes. I’d tried Buck Hodges old blog post on removing the old workspaces (see http://blogs.msdn.com/b/buckh/archive/2006/09/12/path-is-already-mapped-in-workspace.aspx), but that didn’t work; I kept getting “TF14061: the workspace <workspace>;<user> does not exist”.
I finally just used the Status Sidekick, searched for pending changes from the (now nonexistent) user, and clicked on the “undo pending changes” button. It worked better than any of the other tools I’ve used. You can find it at http://www.attrice.info/cm/tfs/index.htm.