So you're setting threadedObject.delegate = nil in your delegate object's dealloc, but the threadedObject is sending subsequent messages to your delegate? The doesn't sounds like a retain-release problem. Wouldn't the same thing happen when setting threadedObject.delegate=foo? Messages could still get send to the old delegate if you haven't done your synchronization right.
Missing the forest for the trees. The problem is that the old delegate will be invalidated before it deregisters itself, because it will not deregister itself until it is invalid (during -dealloc)
