Hi,
one of the novelties intersante be incorporated in the new version of Team Foundation 11, is the concept of Team/team. While we can think that a team is an evolution of groups of TFS, is rather a concept oriented towards achieving a better management of the work done by a team.
Since access to the form of Team we can access directly to:
- View Backlog
- View board
- View WorkItems
- Manage Schedule and iterations
- Manage Workareas
When we manage a Team, we can add new users directly from the new Web Access. In the following image we see as I have added a user showing my ego 
In the form of editing of the information of the members of each group, we can see that groups are the same and obviously manage groups from this interface.
Finally says what ás interesting IMHO, the definition of the groups is carried out at the Team Project Collection. This means that we don’t have to replicate the same set of permissions to the same groups of TFS in each TP, but that the central administration from the concept of Team already us gives this capacity.
Greetings @ Home
The Bruno
El Bruno 