Looks like we've gotten some spam registrations lately. The new members don't seem to show up in the member list on the homepage or in the network admin (as far as I can tell), but in these last two cases, the registrations successfully create blogs at signup that now exist on the site. Will forward specific info to you via email.
#1 Updated by Boone Gorges over 10 years ago
I introduced this bug in the last release. It was related to #1515.