Kevin: The Guardian (where I worked from September 2006 to March 2010) has launched a WordPress plug-in allowing people to take full feeds of their content for free as long as they agree to display Guardian advertising. That's an extension of ad networks, and I'm not entirely sure that there is solid evidence that this will add significant revenue, although much of the data we have must be understood in the context of the recession. I do see some interesting possibilities with respect to building a blogging network. Mathew Ingram explores that well in this article.