Henry Blodget uses his analytical skills to find Google's secret sauce. This may be it, but since most sites are still in the dark as to whether a person that arrived actually buys product, Google's ads may be only a rehash of banner advertising (with a twist). If that's true, Google's only real innovation as a business was its ability to sell click-throughs to advertisers as something that is more cost effective than impressions. They succeeded where many before them had failed.But does it really offer higher rates of purchase for people that arrive on the site?Question. Has anyone actually bought something through a Google ad? Have you even clicked on one (other than to test the system)?