http://labs.google.com/accessible/ Someone posted this on Matt Cutt's blog, I know my site ranks much higher. I wonder if some filter are turned off or if this is a different algorythm.
The algo is different. It shows favor to "cleaner" sites. Easy to read text, clean code, W3 compliant, etc.
I think anyone who practices SEO should make it assesible its so unfair when people stuff alt tags so that people who are disadvantaged who use specialist browsers get confused when there browser reads out a string of keywords.