For those who happen to have a blog (and who doesn't these days?) you are probably aware of intensedebate. It's basically a system of threaded comments that you can plug into your site and take advantage of... well, now that I look back after uninstalling it I really don't see an advantage, but I'm sure there are some.
In any case, one of the things I was hopping for - when I installed it as a plugin for wordpress here on Sugus - was that it would allow me to have open comments (i.e. no captcha) but still protect me from spam. I mean, they do deal with a lot of comments, so they are probably good against spam also, right?. Not really. This morning I checked my comments area and found 120+ spam comments, most in Russian. I am an international kind of guy but I'm pretty sure I don't know that many Russian speaking people.
Also, for the past month, I have been getting a lot of these spam comments to moderate. It seems that no matter how many I mark as spam there will always be new ones (again, Russian mostly).
But I digress, so my point is: If you are going to make a system to manage comments, make damn sure you figure out clever ways of dealing with spam or no one will ever use them. At least, to be a little constructive here, give the proper tools to the site owners who will moderate the comments, like allowing certain domains from posting comments (for instance, I noticed a lot of these comments came from different accounts at the same Russian email domain).
And this is just my small blog, I can only imagine what bigger blog owners go through. Maybe they don't use intense debate and rely on captcha like I will once again...