The tag wiki for tfs-service currently says:
tfs Stands for Team Foundation Server , where tfs services refer to a server for Team Foundation, where you can view the services that Visual Studio Team Foundation Server uses and the Web Service application pools that Team Foundation Server installs. Team Foundation Server includes many services that run on the application tier.
Both of the questions which currently have this tag are instead about the new Team Foundation Service (http://tfs.visualstudio.com/).
I see no value in this tag if it is truly intended to have the meaning currently described in the wiki. I would prefer it to refer to the new hosted service.