I and others have been noticing a new kind of blog spam. Essentially relevant comments, being written by real people but linking to spam sites. I have noticed an increased number of these types of comments.
It is apparent that the battle on the comment spam front is starting to use real people. It is very apparent when you load the linked URL, they either try to link it from their contact info or are trying to hide a hyperlink in a period or single word so that it is not so obvious when you view the comment thread.
They are being pretty smart about it because a recent spammer I caught had left 10 comments without any external links. I assume this was to build trust within the system before he startrf to drop external links.
Bots are relative easy to beat but if spammers are using real people to leave relevant comments linking to their spam sites this will be a bigger challenge.
Talking with other bloggers with higher page ranks they are seeing similar tactics. I am at the point where I will ban any external URL’s from being posted by commenters.