Did that title grab your attention? Well, it was mostly meant as a joke but read on.
I think open source is great (well, except I think GPL is evil but that's another topic). But, lately I've been trying to figure out a way to fix the comment spam problem. Comment spam is generally when someone writes a script to automatically scan the web, find blogs and post ads for crap. Various ways have been tried to stop it but like e−mail, the spam still gets through.
People who run movabletype seem to have some of the worst problems as they are one of the largest targets. Write a script to spam one movabletype blog and you've generally covered all of them. The really bad part is it makes the web less usable. It seems most people that run blogs are forced to turn off comments on older topics so that after a couple of weeks you can no longer leave a comment on one of their posts. That's probably not a big deal if it's just a "here's what I had for breakfast" kind of post but it's a much bigger deal if it's the kind of post that would benefit from comments over time. For example my posts on Japanese CE or Japanese Input on XP have been up for years and still get relavent comments.