ProBlogger: "Google determines a quality score for every blog post you write based on more factors that most of us have ever really understood." Some of the factors:
1. Feed readership as measured by extrapolating Google Reader subscriptions
2. Click-throughs on search results in Blog Search
3. Presence on high-quality blogrolls
4. Inbound social bookmarks
5. Personal conversations (gmail, chat) ?
On a weakly related note, Google says it will introduce online presentation software to complement its Spreadsheets and Docs. Won't it be cool to be able to create slideshows that could then be incorporated into Google Widget Ads? Well, maybe not cool, but definitely easier than doing video ads.
Why Blog Feed Readers Unsubscribe