I think now as normal adsense publisher we can put more than 3 ad units. I dont know its officially allowed or announced. Normally if we try to put more than 3 adunits on a single page, for example if we ad the 4th adsense ad unit on our blogs page its didn't displayed. Today i put 4 adsense units on my blogs page and all are properly dispalyed.... So far i can't find any update from Google's official Adsense blogs. Any idea about that?
A mistake on thread Now as normal adsense publisher we can't put more than 3 ad units on a single page.