I recently used WordPress as a CMS, and I think it was a brilliant move!
I had never thought of doing this until it was suggested to me, but it makes perfect sense, especially if the end user will be a non-technical type person. Wordpress is built so that the most basic user, with little to no experience can get around it and make some changes without too much hassle, so I’m pleased with the way this project turned out.
The website where I used this is www.sentrik.com.au
UPDATE: I just stumbled across this blog post on using WordPress as a CMS, there is also a bunch of links at the end of it which may be helpful.
http://www.graphicdesignblog.co.uk/wordpress-as-a-cms-content-management-system