As soon as I heard Google's announcement on preventing comments-spam, I immediately thought of another use of this technology. But, wouldn't you know it, Scoble already brought it up. In fact, he makes it the center of his post, and leaves the "comment-spam prevention" as an aside at the end.
I think Robert's on to something. Getting rid of comment-spam will be a (hopefully successful) behind-the-scenes, implemented by the software developers and the search engines solution. But the effect on us, as web users and content producers will be to have the power to express even this simplest of editorial statements about our links.
But, if we're wrong and people don't use it enough to change the nature of linking on the internet in any meaningful fashion, this could still be a great win. So many people have turned off their comments in frustration due to comment-spam. If this gets rid of that, many blogs might be able to become more conversational, and, in turn, keep the blogosphere more responsive, interactive, and community-like.