Folks, I'm seeing a general up-tick in the number of spam comments making it through the CAPTCHA here over the last few weeks. It's only been about one comment a day, so I can keep manually erasing them when they happen, but if the frequency picks up much more beyond that, I may decide to turn on Comment Moderation (which would mean that all comments would be "held" until I get 'round to publishing them). I'll make that announcement if it becomes necessary, but there it is.
By the way, I've also noticed something that Will Duquette noticed: occasional spam comments that are actually "on topic", and only include a commercial link either in their signature or at the end. For my purposes, unless you're someone I know trying to point out a product or website that may be germane to a specific post, I will assume that any comment containing an obviously commercial link is a spam comment and delete it. My decision's a bit more Draconian than Will's, but he's probably nicer than I am, anyway.
For more information, see my official comments policy.