[giantrobot]

> For reasons I can't quite put my finger on @user seems a much better sigil than ~user to me, so I'm not bothered that it's become popular.

I think this makes sense if you pronounce the action. On Twitter you'd tweet [at] user(s). I think it made even more sense back in the Twitter via SMS where you had to send a message to Twitter's number but direct at a particular user.