In the inbox it shows when you have been mentioned in a comment. If you follow a lot of projects there will be a lot of comments and updates in the inbox. It would be good to have a separate notification list between Activity and Archive where you only see the comments where you have been mentioned in. The reason I think this would be good is because these are comments that you normally need to act upon and then you could look at them first and after that you can look at the regular inbox and all the other updates.
The comments with mentions should be visible in the regular inbox as well so this should just be an extra feature.
I think this would help a lot!