Well from past sometime you mighthave observed that google had increased the default ads size of their units if you have turned on the default option in adsense dashboard while creating a unit.

As a follow-up to last week’s launch of font size controls, we’d like to let you know that we’ve just increased the default font size for AdSense ad units. This change will affect your ad units if you haven’t yet customized your font sizes, or if your ad units are set to ‘AdSense default font size’ — you’ll notice that the text in your ad units is now the equivalent of ‘medium’ instead of ‘small’. We decided to make this change based on publisher feedback and our testing, which showed that this increased font size improved performance.

Does it helped publishers ?

If you ask me then i would say it helped a little more as we are able to get some attraction in the eyes of the visitor. But again you ad placement matters a lot. How well you mix your content along with ads displayed is also a technique.You can see at my this blog how ads are displayed as they are generating me a good amount of return back.

Keep Experimenting :

For adsense and all other ad network i would suggest you to keep experimenting with