I asked the question on the linked blog [1] The official reply was " For now, we are starting with WordPress.com users but look forward to working with folks like yourself who are self-hosted. "

Sweet!

1 - http://en.blog.wordpress.com/2011/11/29/wordads/#comment-143... (that # href doesn't seem to work too well, do a seach for 'grecy' and you'll jump to my comment and the reply)

This boggles me as well, wordpress has a huge install base and them making a sanctioned plugin for these ads would give a much wider audience to advertisers. The only reason I can possibly see wordpress.com sites as the reason for the rollout is that they are doing a limited release in order to not get overwhelmed.