wignu I did. The diversity of how this extension can be used is immense. So simply hiding all private discussions per default is not a solution. If any implementation of such a feature should be added, it should play nice with the other extensions.
Having said so, being able to lock down who can create and update recipients per tag should allow for pretty flexible set ups. You could create a tag hidden to the public which has the required permissions for members to create a private discussion with just you.
One thing I do consider is allowing for a support desk-type of usage. This would mean something like the ability to specify a tag and forced recipients in the admin, this would be very powerful if combined with the tag permissions.
