I've been thinking about how to implement inline commenting. (Aka commenting on a comment) and I think I will be able to begin working on that today. i think the limit will be 1 inline comment per tree. That means you will only be able to comment on the main comment thread and will not be able to comment on a second comment in a main thread.
Along with inline comments, comment notifications, and notifications in general) should come along with this, but may not be implemented right away.
Now the less interesting addition: Mass Mail
Admins now have the ability to message all users at once. At the moment this system is clunky and will probably break the site if we had 10,000+ users (Maybe even a few hundred). For now, we're fine, but I will be incrementally tweaking the feature to be a bit more friendly to larger amounts of users. A test message as well as update will go out later today detailing what this feature will be used for.
If you have any suggestions, leave them in the comments below!