With all the splogs and spam issues, I don't feel safe automatically promoting random posts on my front page or elsewhere. However, I think what would work is to approve certain blogs or users (e.g. Supporters?) as "trusted" and create a RSS feed of their posts to be the source for whatever... Posts on Recent Site-Wide Posts on my front page, Twitter, Facebook Fan Page, etc.
Now that I think about it, such promotion could be another great incentive for users to become supporters.