Google's Efforts to Battle Comment Spam

Google is attempting to enhance the web experience with its recent proposal to battle comment spam by using the rel="tag">no follow attribute (rel="nofollow") on hyperlinks on sections of sites that allow users to post comments and links. I think this is one case of the intention being good but the implementation being wrong. They need to figure out a way to battle comment spam without killing the comments section. I have to agree with John Battelle's views that this may be a double-edged sword which can reduce the incentive for users to post intelligent comments in the comments section. There is a lot of insightful dialogue in the comments section which may reduce and eventually vanish if that content and the creators of that content are not valued by search engines.