“ The Team Foundation Server Power Tools (October 2008) introduced a new “Team Members” node, which offers the ability to quickly identify which subteams and actual team members belong to a TFS team project. Additionally you can see their online status. Support for Office Live Communicator and Windows Live Messenger is already built-in. There is an API to extend this to other IM software as well.”
But if you are not using Windows Live Messenger or you are not logged in, you’ll get one of the following error:
You can change or disable your collaboration provider to avoid this messages:
Right click Team Members -> Personal Settings
Press “Change” button for collaboration provider
Choose your provider.
Popularity: 6% [?]
considering the amount of comments it looks like this web log is really popular.