tedster - 6:59 am on Nov 18, 2011 (gmt 0)
Google's idea seems straightforward to me.
1) Organic search tries to send traffic to a page based on the relevance of the indexed page content.
2) If that content is hard to notice because of advertising or some other above the fold layout issue, then Google doesn't want that page to rank well, no matter how "relevant" the text content seems to be otherwise.
Using content only as search engine bait to shove ads at the visitor is a bait-and-switch tactic. I hate using "find in page" search to locate the relevant keywords, and most people don't even think to do that.
This is not some conspiracy in my mind; this is a service to the Google Search user.