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 think ?
I am agreed with mitz. It is like a popup. Though Google's Tos doesn't prohibit you to do that directly It is not a good idea to provoke user to show a specific Ad Space. In my sense it will get higher CTR which is also very dengerous to get google's attention. You should better ask the Google Experts before applying the concept.