This spam is getting out of control...we really need some kind of CAPTCHA on it...
From what I've read about that reCAPTCHA plugin, it seems that it would minimize inconvenience pretty well:
When do CAPTCHAs get displayed? How do I tune this?
By default, CAPTCHAs are triggered on the following events:
New user registration
Anonymous edits that contain new external links
Brute-force password cracking