I want to be able to share some stuff with group A (e.g. old friends), other stuff group B (e.g. project collaborators), with the option of having stuff I post

I want to be able to share some stuff with group A (e.g. old friends), other stuff group B (e.g. project collaborators), with the option of having stuff I post to group A being invisible to group B (and vice-versa). I don't think FriendFeed can do this, but I'd be interested to learn if I'm wrong. [edit: related thread: http://news.ycombinator.com/item?id=451491 http://news.ycombinator.com/item?id=451491 ]