There's a thread dedicated to this at Digital Point. It's quite lengthy and has been going on for quite awhile. I'll go and see if I can find it and post a link to it.
I've just started doing this for my dedicated article and adsense sites. But I've put a light border underlining the images so it's a little bit separated and they aren't exactly lined up. - Depends if you get 2, 3, or 4 ads in a 728x90 banner, so I implemented it into the header. But it does improve the look. They are new sites, so I don't have much as far as history to go on, to show any improvements:
My sample sites which I've implemented this on:
myspaceslayouts.com
investmentsguides.com
hairlossguides.com
mortgagesguides.com
Here ya go:
Just found it.
I'd like to have other's opinions and help to improve as well. I have a good CTR, but my traffic is minimal. But my sites are all young.
http://forums.digitalpoint.com/showt...sense+pictures