During the week of August 19, I noticed a substantial downturn in Adsense revenues, likely due to new Adwords changes, and not "Smart Pricing". I had made no changes to my site/ads in any way, nor did I have any downturns in traffic. Anyways,I found this good article on the recent Adwords changes that I thought might be useful: http://www.traffick.com/articles/internet-marketing/advanced-adwords-strategies.asp