I recently launched the portfolio site for my company, Roycroft Design. Check it out: http://www.roycroftdesign.com/
The whole site runs on WordPress. I created a custom post type for the portfolio projects, and a custom taxonomy for it as well. It was interesting to figure out how to get them to work for our purposes, and to figure out how the new features (mainly with 3.0) would work. They definitely helped to utilize WordPress as a CMS, with less hacking than was required before.
I'd love to hear feedback if you guys have any.