Nofollow No Good?

In Google Web Accelerator, Dylan calls nofollow a failure.

Since its enthusiastic adoption a year and a half ago, by Google, Six Apart, Wordpress, and of course the eminent Dave Winer, I think we can all agree that nofollow has done nothing. Comment spam? Thicker than ever. It's had absolutely no effect on the volume of spam. That's probably because comment spammers don't give a crap, because the marginal cost of spamming is so low.

Worse, nofollow has another, more pernicious effect, which is that it reduces the value of legitimate comments. Here's how: Why should I bother entering a comment on your blog, after all? Well, I might comment because you're my friend. But I might also want some tiny little reward for participating in a discussion, contributing to the content on your site, and generally enhancing the value of the conversational Web. That reward? PageRank, baby. But if your blog uses the nofollow tag, you've just eliminated that tiny little bit of reciprocity. Thanks, but no thanks. I'd rather just comment on my own blog. And maybe, if you're lucky, I'll link back to you.