Adoption Item and Affected Teams
One answer
Back on August of 2010 this may not have worked (at least on whatever version you were using at the time), but even as far back as 3.0.1.x (tested on 3.0.1.5) and perhaps earlier, Affected Teams is available as a query condition (and, since the conditions are sorted alphabetically, it's the very first condition on an English language system).
I had no difficulty creating a new query called Adoption Items for Team A, adding the Affected Teams condition to the query, selecting Team A for the condition, running the query and seeing a list of Adoption items. It should be simple to make a query like this and install it on the Team's Dashboard. If you set the Affected Teams attribute to be filled in when the query is run, you can use the same query on many team dashboards as the fill-in value will be configured when the query is bound to the dashboard widget.
