Just saw an inteview on CNN with an employee from
Nielsen Ratings that page views and clicks are no longer reliable measures for onlie advertisers. In short a single click get your viedo started. The same with games and other webapplications. So he concluded that clicks and number of page views are no longer a reliable metric. It will discriminate against online game sites, video sites, instant messengers, iTunes and application sites. Therefore advertisers should look at other new unbiased metrics like time spent on a site. He also predicted that advertising would increase on game and application sites.
My own view:
This is a result of the web getting more and more a space for entertainment. AJAX was the first technology to reduce the gap between desktop and web applications. The web 2.0 has absolutely started.