Yes, There is a Page Fold
The terms “above the fold” and “below the fold” come from newspaper design, where information most likely to catch the eye is placed above the fold of the front page in order to attract attention and readers.
This same idea has been used in web design, but sometimes it's used to the extreme that you don't want to put any information below the fold and make your readers scroll. This is obviously a distortion of the principle, as one can easily see just by looking at the design of newspapers. When did you last see a newspaper that was completely blank below the fold? I'm guessing never.
There's a popular movement in the web design community recently that is trying to eliminate the page fold mentality. From what I can determine, the problem they have is primarily with the distorted view that all important information should be above the fold, but they're also throwing the baby out with the bathwater by arguing against the idea of there being a fold at all.
It's true that scrolling is an easy and natural event for the average web surfer these days, so scrolling isn't really an impediment to consuming content. But it's not true that what is visible on screen on the first page load doesn't matter.
If what is visible on screen doesn't entice the users to bother scrolling to see the rest, then you've lost out.
What bugs me most about this is that people arguing against there being a fold, appear to usually design their sites precisely around the idea that there is a fold. No, everything isn't visible on screen, but what is visible on screen is often the most eye catching and enticing part of the design.
What I'm trying to say is that there definitely is a “fold” on a website, and even those who say there isn't design like there is. This doesn't mean it should be treated the same way as a newspaper fold, or that there are necessarily hard rules about how to use the fold. But it's there, and should be recognized.