4 content units per page

Hi guys,

We all know that AdSense allows up to three content units per page. I have recently run into some sites that display 4 content units per page.

"Currently, AdSense publishers may place up to three AdSense for content units on one webpage. You may also place a maximum of three link units and two search boxes on each webpage."

How this is possible? Are these guys some kind of Premium Publishers were google allows the to display more ads per page?

 

Anyone (who is not a premium publisher) can add as many units as he likes using iframe.
But, that's against adsense TOS though.

 

Have u some references about using that technique? some Urls maybe?

 

go to ezinearticles pick one of their articles. 4 content units- 1 on the top, 1 bottom, 2 on the side. There is few more. Smaller sites and 4 content ads. Not sure how they get this privilage but it kind of cool.

 

True, but this a way of getting yourself banned.

 

They are certain limitations available for Regular Adsense Publishers! Although Premium Ones have extra advantage over Regular to place around 3 links unit ads of each type in the one page

 

I c so as i was suspecting "Premium Publishers". I am wondering what you have to do to become a Premium Publisher.