I have been thinking about it for a while but Steven Rubel says it better than me. So please read that. New web application make the ruling principle of page view less relevant and maybe totally irrelevant (one of the guilty on that one is ajax that makes page refresh inexistant). Quoting
The page view does not offer a suitable way to measure the next generation of web sites. These sites will be built with Ajax, Flash and other interactive technologies that allow the user to conduct affairs all within a single web page - like Gmail or the Google Reader. This eliminates the need to click from one page to another. The widgetization of the web will only accelerate this.
I think it is about time marketers and media agency pay more (REALLY MORE) attention to other pararmeters like loyalty/churn, user lifetime, time spent on website, time spent per page, ability to lead conversion, level of influence, advertising memory and awareness generation, and other things that we are discovering as we speak.
Internet is a media that is way more complex and sophisticated that only page views. So why advertising should not be?
Of course this is not for tomorrow but within 12/24 month will hear much more about that and Comscore/Hitwise and Nielsen will have by then to provide real alternative way to measure and benchmark websites. But internet companies will also have to learn that and educate the market with what really matters: the value of an end user.