In an earlier discussion about commenting Kris mentioned using pingback, but...
Spam is a problematic issue. I had to enable comment moderation not because the Captcha was too easy to come by, but because apparently real people are adding genuine comments and are actively abusing the URL field to point to their commercial (or virus-infected) websites.
Would it be possible to comment an article on the originating blog instead of creating your own article. I found it very annoying when you did that to me, and now I see you doing it again :-)
I prefer discussions being held on the original article's blog (so people reading it can read your remarks) rather than having comments being posted as blog articles on different blogs. (That would only work for people reading a Planet anyway)