War on comment spam

Mark Glaser posted an excellent article today about fighting comment spam. Suggestions include turning off comments on old posts, using redirects on links in comments (preventing Google from indexing them), and mandatory registration or preview pages (making it more difficult for robot spammers). In the article, Dave Winer makes this excellent point:

While [Winer] thinks that all the war tactics by bloggers will ultimately fail, he says that Google itself could solve the problem by adjusting PageRank so that it doesn't weight links from comments as heavily as links within blog posts or on other pages.

Joel on Software also has a good post (scroll down to "Discussion Group Software") where he talks about using Bayesian filtering to detect comment spam and META tags to prevent search engines from following links on comments.

[Thanks, Niall Kennedy, for pointing to the OJR article]