SE has a new GIS blog. It uses Wordpress (WP).
I see these shortcomings:
Voting not supported for blog posts/comments.
Identity management - bloggers need a WP login, comments require captcha.
No trackbacks from questions posted in the main site referencing blog posts.
Each of these could be addressed if SE enhanced the main site to support blogs.
SE has Q&A nailed - now it's time for A&Q. A blog post can be thought of as an answer in search of questions. Q&A threads spawned in the comments section of a popular blog post can become quickly tangled. By linking questions on the main site with blog posts (and vice versa) SE could solve this.
Who knows, this might attract bloggers who've fallen off the wagon, too tired to sort through and answer questions posted in their comments section. By blogging at SE, they could focus on the highly voted questions.