Blog or CMS?

A visitor recently suggested WordPress for the CMS poll. Shortly after making the suggestion, another email was received asking to ignore the first email because they had seen the separate category for blogs (you may have to scroll down a bit to see all the polls). This brings to light a question that has been in the back of my mind for a couple of months now: Is it necessary to have a separate category for Blog software?

I think most people would agree that WordPress is not a full-blown content management system. However, it can be extended beyond just a pure blog and a lot of people use WordPress as if it were a CMS. Also, Nucleus is branding their platform as a CMS.

The line between content management systems and blog software is getting thinner and thinner. I'd like to ask visitors for their opinion. Would it make sense to merge the Blog category with the CMS category or should these remain distinct?