A while back Google announced that it was “adjusting” its algorithm to address a problem with some sites that carried a lot of banner advertising.   Specifically, Google heard complaints from searchers about coming to a website with so many banners advertising that they had to scroll way down before finding the content.   Thus Google stated it will be “devaluing” sites that carry so many banner ads that the actual content falls below the fold.
I can say from firsthand experience that Google is not kidding about this. I had a site where any content that fell significantly below the fold did NOT show up in its cache. The caveat is that the site in question did not have ANY ads and the content all appeared to be above the fold,  but it was structured incorrectly with tables so that the content “looked” to the visitor like it was above the fold, but to Google, it looked well below the fold.
I as was able to correct all the pages by adding <td> tags where appropriate. I could see the issue when looking at the site in Firefox webmaster tools and going to Outline>outline table >tables. Once I did this, I could see the content in question drop way down below everything else. This was despite the fact that in IE 8.0, 9.0 and Firefox 10.0 the site looked normal.
Moral of the story, check how the content is cached. I do this by using the Google page rank tool bar where you can click on a drop down “see cached snap shot of page”, then clicking on “text only” this supposedly shows you what content Google has in its cache. Of course who knows what Google really is doing?  
Your site could be punished for content appearing below the fold, even though it does not appear below the fold.