I have been running this blog on Wordpress for about 6 months now. For the first 3 months, there was no spam at all. The next 3 months I got some, but not a big deal. Over the past few weeks, comment spam has gotten completely out of control. I delete all of it, so (as far as I can tell) it does no good to the spammer. But even so, I am/was getting over 100 spams a day, everyday.
As of 01/10/07, I have implemented Akismet. I am cautiously optimistic this is going to solve the problem.