'rel="nofollow"' WILL NOT Stop Comment Spam
I've seen a lot of posts in the last 24 hours about Google's new rel="nofollow" attribute on hyperlinks. Both Neowin and Google claim that this method will stop comment spam. I cannot stress enough that this viewpoint is absolutely incorrect. An attribute will not stop comment spammers at all. The only thing that the attribute does is stop the Google indexer from adding google-juice to the link. That's it. The link is still there for the users on the site itself, and if you run a .Text blog, you'll still get bombarded with e-mails every time a new comment is posted.
The best bet is to put in a multi-factor comment-spam protection solution that stops comment spam before it ever gets posted. A combination of a good CAPTCHA tool, and comment spam verification from CommentSpam.org is an excellent deterrent.
All rel="nofollow" will do is let Scoble link to people without increasing their Google ranking.