I was a little curious when we'd get a ticket for this. It seems to be from a relatively recent change (within the last week). I vaguely recall snippets on irc discussing a trac upgrade - is it from that?
For my part this doesn't matter - it's was trivial to filter them out.
I've disabled this for now (I think). The admin interface about notifications claims it was sending account creation information to torproject-admin@ but for some reason it was including tor-bugs@ which is on the default notification list.
weasel, is it cool to leave this disabled or do you want me to find a way to only notify torproject-admin@ ?