I see 7 "Ads by Google" on this page - http://www.yourphotoshopguide.com/index.php?action=showtutorial&tutid=26 You have to scroll all the way down on the tutorial part, and then there's a bunch of them at the bottom.
Premium publishers negotiate the terms of their contract, so how many ads they put on is dependent on what they negotiated for and what Adsense agrees to. But in a nutshell, Yes, they get to put an unlimited number of ads on their site.