I think that the eye tracker results can be explained by Don Norman's book Emotional Design, where he speaks of the three aspects of design: visceral, behavioral and reflexive.
A good example is car driving: when you're learning, it's behavioral. You are being very careful of when and how you apply the brakes, both of your hands are firmly on the steering wheel, and you pay extra attention to signal lights. When you become an expert driver, your driving becomes reflexive: you know instinctively where the pedals are, and you can make a right turn as easily as you walk down the street. You are now able to change the FM station while driving, talk on your mobile phone or with a passenger, etc.
Web surfing starts behavioral and becomes reflexive. At first, you pay attention to everything on a web page, but then you get used to certain standards and you start surfing reflexively. That's why following certain standards is very important. I will bet that the developer that @Steve showed his website to was expecting a "call to action" button like one of these:
So he completely missed the text-based "Try it now" link because... it simply doesn't look like a button or even a link. It looks more like a headline. Making it bigger is not going to help because it will then look like, well, a bigger headline! At the reflexive level, it doesn't work. In fact, when I clicked on regexhero.net, my eyes were first attracted to the "Buy Regex Hero Professional" link because that looked more like a button: