I myself hacked the cb login module to duplay PURPS (from pragmaticutopia.com) pending game notification.
But you have to realize that for notifications, a 'unread' or 'pending' state has to be associated to the item you want to notify. Sorry for my english if this is not clear.
I mean, you have mail notifications because an email has an unread state in the DB, or 'pending' state PURPS Game.
As profile comments don't have an unread state, it would be hard to see if the profile owner has seen it allready... for not showing the notification when it's useless...