As we mentioned before in one of our summaries on Google’s regular changes to their algorithm, one of the factors that Google will be considering when deciding how pages should be ranked in search engine results is the layout of the page.
In order to combat pages that are overloaded with advertising, Google will be giving preference to ads which have content above the fold, (visible without scrolling in other words).
This is in response to user complaints about the difficulty of finding content on a page after following a link from the results page, and Google has explained that sites which don’t have much above the fold content may find themselves affected by this change.
In their Webmaster Blog they say that the change is supposed to affect less than 1% of searches, but that ensuring that there is relevant, above the fold content on your site will be a positive signal in terms of ranking in search engine results.