I was doing that today and I wondered if it would be possible to extend the "/msg me when a reply to one of my posts arrives" functionality and be able to get /msg'd when a new note is posted in a thread I have marked as interesting.
Add a button, say, at the top of each thread "Subcribe me" ( can't resist the Alice in Wonderland reference ). If you wanted to be /msg'd when a new post was added to thread, click the button and you are subscribed.
There would be, at my first glance, two hard parts.
The first would be some way of knowing that the interested party had already been /msg'd and not /msg again until they had cleared the first. This is primarily to keep from getting overwhelmed in the CB on a busy thread. It is not currently provided on the "/msg me when a reply to one of my posts arrives", so maybe vroom says caveat emptor and that is the risk you take for subscribing.
The second hard part is unsubscribing. I would rather not clutter the thread interface too much - it is bad enough already. Maybe another screen could be added off of each user's account to manage subscriptions - a person could unsubscribe from here and possibly even subscribe if they had the node id.
Is there any value to this? Can it be done?