yes, I just went and checked and sure enough, the communities I follow are in the list right along with the users, so if I select a community name, all the tags that comm uses come right up and are available.

You could set it up to only show you certain tags, or to not show you other tags, i think it works both ways-- so you wouldn't, I think, see untagged posts. I'd have to mess with it to be sure.