Well, the change is just about done; pizaaplanet has graciously offered to design buttons (since I suck at graphics stuff), and once that's done we'll be able to push out the functionality.
One thing I'm not sure of is whether people should automatically get resubscribed to a thread if they post in it again after unsubscribing. Neither pizaaplanet or I uses the new replies feature, so it's up to the people who actually do use it. What do you guys want to happen?