[Question] LW Dev question: FB-style tagging?

As LW is an intellectual **community** where people get to know each other and know “who knows what, who’s working on what” it seems like something like tagging people FB-style in specific posts/​comments is a very low-hanging fruit. (Of course you should be able to silence people from tagging you or sort taggers by some score). Is this in the pipeline, or has been ruled out for some reason?