Mollom moved from a private beta to public beta today. I've been fortunate enough to participate in the private beta and can say this stuff rocks. There are plenty of methods of protecting sites from spam and bad content, but this is by far the best so far. The problem with many systems is they treat legitimate users as the enemy. At least with traditional CAPTCHA systems is that they challenge the user for an answer before the user has provided any information to suggest they should be challenged. Users pay the penalty for the bad behavior of the spam bots. There are systems that work around this and some like Akismet have done pretty well on this site. The problem, however, with many of these services is that they can still be gamed to a greater extent. And, since the spambots don't recognize that their attempts to add content have been unsuccessful they merrily pound away on the server. The other methods also generally call for administrators to monitor things pretty closely. With all the great spam tools there would still be a couple of spam posts a week that would slip through on this site. During the transition to Mollom a bot was actually attempt to post. In the few seconds the site was unprotected a couple of posts slipped through. In the weeks since nary a errant post has been made (aside from one on an article which should not have been configured to accept comments but that wasn't spam).
There are sites like GoDaddy that take this to the extreme with CAPTCHAs for logged in users all over the place. Granted they have problems with automated logins and people abusing services, but somewhere the madness has to stop and they need to come up with a better solution.
But let's take a look at the impressive results on another site. The site is pretty neglected and doesn't have a lot of traffic. But benign neglect made it a haven for spambots. They loved to post away. The graph below shows the spam posts since installing Mallom on the site.
So not only did Mollom successfully keep the spam off the site but the 'bots have started to leave the site alone. Quite impressive results. Will they be back, on high value sites they surely will. The notes on the public beta mention that some of the issues from the private beta have been fixed. Those issues sometimes caused me to feel like Groups.Drupal.org was out to get me asking for a CAPTCHA on every post I made.