I had someone create an account at my wpmu site (1.2.5a), and they used 'wts9mv33gxtqs57' as their username (obviously a bot). The weird thing is, there is not email address listed in the details of their blog, and they 'self deleted' the blog, so I'm thinking they were testing if some account creation method (other than standard signup) could be done.
Has anyone else seen anything like this?