The Super User blog is an interesting read and is a good way to highlight interesting topics within their community.
I think Stack Overflow would gain at least as much from having its own showcase on discussions of interest such as "Question of the Week", analysis of a particular hot topic, humourous discussion threads on questions or chats, or other such material.
I'd say there is plenty of material available on a weekly basis that could serve as a topic subject matter, but is there enough interest within the community to sustain a blog on a weekly basis, and do people feel that a blog would add to the community?