just hypothetically speaking, but wouldn't it be great if adsense gave the option to switch the adsense action event from onclick to an onmouseover. might be occasionally annoying for visitors but i doubt publishers would mind!
wouldn't it be similar to popups? Would be good for the publishers, yes, but for the advertisers they would end up with traffic that isn't really interested in the site.
One of adsense adventages is that their ads are not so annoying for visitors. And I think this is good.