You can now tag other members in your posts, profile posts, comments, etc. For example, if I wanted to tag Rhys in this post, I could just type @ + Rhys to get Rhys - a neat little box will even pop up when you start typing with a list of suggestions. The member who you tag will receive an alert that he's been tagged in a post, so don't worry about them not noticing. It's just like tagging someone on Twitter!
Just tested it out for the first time. More boards need this future. I hate quoting people when they were the last poster but maybe I'll train myself to use this instead so they still get the notif.