I'm not sure why there's so much consternation about the rel="nofollow" attribute, both in the comments on this blog and around the blogosphere. It's intuitively obvious to me that this is a good thing. Why? Because the choice of which URLs on this site that I think are worth linking to and worth indexing are now back under my control. That's a good thing.
Like I wrote in a response to my original post, even though I moderate comments I still don't know for the most part if the person leaving a comment is doing so to contribute to the conversation or to promote their own website. I have suspicions that many times its the latter. Like I've written a million times, this corner of the web is mine, and though I invite people to comment here, it's still my weblog. Now that I've added the nofollow attribute, I know that if there's a link on this weblog that's counted by the indexes, it's because I have given it my seal of approval.
So whether this fixes comment spam or not, I think in general if web results are going to be ranked on links among other factors, then they should be more "intentional." If this has the effect of pushing people back to their own blogs and out of my comments, I think that's great. And if it has the effect of wacking my page rank as well as others, so be it. I'd rather have a more purposefully ranked system, then watch it being gamed as it is now.
What I don't see is how anyone thinks this is going to "break" anything. The ranking system is being abused currently, this is a way of curbing that abuse, as well as tightening up the system in general anyways. So from now on, if a web crawler sees a link on this site without the nofollow, it's because I as the owner, operator, editor, etc. of this website has approved. This seems abundantly fair to me.
I think there's lots of smart people in Google, Yahoo, SixApart and Microsoft who agree, which is the reason they've agreed to this standard.
P.S. There's already lots of discussion about this over at Anil's blog, so there's not a lot of reason to rehash it all here. I just wanted to state my opinion.