Greg Linden spotted the newest kid on the personalized news block: Spotback. Spotback's "twist" is that ratings drive the personalization. I found Linden's take surprisingly positive although he did find the recommendations a bit off.
The key problem is that rating is work. In this context, it's work for non-obvious impact. If you rate a bunch of stuff how do you know you're getting better personalized results? I know the last thing I want to do when I'm surfing is rate stuff for the benefit of some opaque ghost in the machine. And this doesn't even touch the issues around dealing with cheaters. Vote early, vote often as we say in Chicago!
Since this personalization transparency issue is becoming a hobby horse of mine, maybe I should hunker down and do some literature review to see how the recommender system and information filtering communities evaluate the quality of their results. I'm starting to think that the best such engine would convince me not that it had "more good stuff" but guaranteed that it "always had the important stuff".