There is a commercial privacy control plugin for CB 1.1. As that one is using database queries to do this task, I doubt that it is compatible with CB 1.2, as the author wasn't available for CB 1.2 RC testings for private reasons.
We are planing to implement such features, probably as a plugin, as most sites don't need it in basic installation, but I can't give a date yet.
Maybe some plugin exists that i'm not aware of.