There's a ton of spam throughout the blog and forum sections. The other moderators and I do what we can to keep remove it from the forums and, when we can, we'll also try to wipe it out from the various blogs. Usually this involves finding all the posts associated with a user ID, reviewing them to make sure they're really spam, then manually deleting each one. Sometimes we have permissions to do that, sometimes we don't. I generally report chronic abusers to administrators so they can remove the accounts entirely.
A big thank you, by the way, to those of you who take a few moments to report spam or abusive posts. It makes an overwhelming task more manageable for the moderators when you let us know about those posts -- we can't all be here all the time! Those extra few seconds you take help us make the forum experience better for everyone (except, with any luck, the spammers)!