Thanks for the looking into it and for the offer to email google, but I was mostly interested in everyone's personal opinion on effectiveness of ads and or legality.

I have seen it in a couple of sites.
Anybody has seen it ?
The adsense stays on its place as you scroll down the page
its a nice effect and it could be getting more clicks then usual
What do you...

I saw on a post of cscgal mentioning A/B testing, I have heard of the term in numerous conversations but, I was wondering what is the concept and how do you actually go about doing it ?

Thanks