Morgan McLintic ponders the meaning of links, rank, and influence. I'm with him up to this part:

Perhaps a more sure way to gauge influence is to count the comments themselves, and the number of participants in those comments and the frequency of times those commenters engage. A lively discussion involving a range of different people, would suggest strong influence on that audience. They are engaged in the content, as evidenced by their being spurred to action to share their opinion.

Well, to some extent. On most blogs with comments, the signal to noise ratio gets lower and lower as the number of commenters rises. This is especially true of the big political blogs; pick an arbitrary political blog that allows comments (the side of the aisle the blogger is on doesn't matter) - and you're bound to see trolls. Lots of them. Happens in the tech sphere too - witness the mud slinging that goes on over at Scoble's place sometime.

There's a point past which comments become fairly useless. Does the sheer volume indicate influence? It might. It's hard to say at this point. The tools we do have - Technorati, et. al. - are still pretty blunt instruments.