AlexK - 5:22 am on Nov 9, 2010 (gmt 0)
Good to mention StopForumSpam [stopforumspam.com] here, I think.
The technique mentioned is well-recognised as an alternative method to SPAM. I report to SFS & remove several such accounts every day. A wonderful feeling: each one removed means yet another spammer auto-banned at thousands of other sites.