Google AdSense now allows up to three ads on high-end devices!Posted by on September 26, 2012 12:24 PM
Google now allows up to three Google AdSense ad units on mobile sites for smart phones.
According to Google help page , you can have three ads on high-end devices and only one (maybe two) on WAP only devices.
“Currently, publishers are permitted to display one AdSense for mobile (WAP only) ad unit on each of their WAP mobile webpages. If a double ad unit is used, please note that it may only be placed at the bottom of each page.
Publishers should use standard AFC ad units for websites formatted for High-End devices. In this case, they should adhere to the AFC ad limit guidelines which allows up to 3 ad units per page.”