I'm in the same boat. I post work stuff to my "Techno-Geeks" circle. Then when I look at the stream for this circle, I see all my geeky friends' cat pictures that they're posting to "Public" or their "Friends" circle. I'd love to have a group feature that works the way circles work, so I'd only see relevant posts when I go to the group-circle, and other people could post to it as well.