WP-reCAPTCHA should stop machine
entered spam
Sorry Jeff, there are any number of nefarious sites out there that provide easy programatic API's for breaking CAPTCHA's. Sadly, a lot of these are done by people in real time, but to a bot that is just an implementation detail.
Here is one: http://www.kourkouta.com/service.php
A while back I wrote an automated program to play Mob Wars (lame I know) for me on Facebook using Selenium RC. Eventually the guy started introducing CAPTCHA's and I ventured into the dark side. I found some shady off-shore company that offered a FREE web service you could upload CAPTCHA images to and get the result. I integrated that into my program, and it never missed a beat.
Anyway, just saying that most CAPTCHA's are little more than a digital nuisance that bots will go sailing past.
And didn't you write a blog entry once upon a time telling bloggers the most effective way to deal with Spam was to just read your comments and delete the spam ;) I think you may have even used a gardening metaphor. But I suppose it is a different world for you now... economies of scale and all.
UPDATE:
Here is the quote and the citation you requested:
I've had plenty of experience with
blacklists. A miniscule percentage of
spammers have the resources to bypass
my naive CAPTCHA. They hire human
workers to enter spam comments. That's
why I enter URLs into a blacklist
every week on this very site. It's an
ugly, thankless little thing, but it's
necessary. I scrutinize every comment,
and I remove a tiny percentage of
them: they might be outright spam,
patently off-topic, or just plain
mean. I like to refer to this as
weeding my web garden. It's a
productivity tax you pay if you want
to grow a bumper crop of comments,
which, despite what Joel says, often
bear such wonderful fruit. The labor
can be minimized with improved
equipment, but it's always there in
some form. And I'm OK with that. The
myriad benefits of a robust comment
ecosystem outweighs the minor
maintenance effort.