I think its course about using Micro Niches for Adsense. and Famous for their AdSense optimized layouts.
The term is used in the advertising and marketing industries generally (not just on the Internet). It's a hazy concept, if you ask me. But it refers to advertising that has a particular "oomph" or magic ingredient or special hook that makes it stand out from the crowd. It's whatever grabs the reader and makes him or her pay attention and then take action. I've also heard people say that a particular TV show or movie has this or that mysterious "X factor." I guess it's something that you know when you see it, but for me it's not that useful a concept. How can you know ahead of time if your ad (or show or whatever) has it? I don't think you can.