Microsoft Live ID Flaw with Registration

I've been trying to get hold of some more information on a problem which has apparently just come to light over the weekend. Article on CIO.com, notable quotable time:

"Microsoft Tuesday fixed a bug in its Windows Live ID registration that let users deceptively register a false e-mail address.

The false e-mail address could then be used as an ID for Microsoft's Live Messenger program, which could trick users into thinking they are chatting with someone who is not whom he appears to be, such as steveballmer@microsoft.nl."

According to the article, Microsoft have since fixed this up but I've heard reports that at least some of the spoof accounts created before the fix are still fully functional...