Nielsen MediaNielson / NetRatings, a leading online measurement service, will scrap rankings based on page views and begin tracking how long visitors spend at the sites.

New technologies like AJAX, podcasting & online videos make page views less meaningful. How much time someone spends on the site is more reflective of its popularity than simply page views.

I think this will downgrade sites like Digg or search engines where people stay for a short period before they move on to interesting links from these sites.

Although Nielsen already measures average time spent and average number of sessions per visitor for each site, it will start reporting total time spent and sessions for all visitors to give advertisers, investors and analysts a broader picture of what sites are most popular. link

I think this is a step in right direction. Page views however still continue to be important for standard web sites and blogs. Also page view matrix is more important if your primary focus is to reach maximum number of potential customers. There is also a logical fallacy in time spent estimates. Any site which effectively guides its users to advertisers site will also reduce the time spent on the site itself. The second issue is that with video sites like YouTube I seriously doubt if many viewers looking at multiple videos are actually interested in checking out advertisement. The people who check out the advertisements are normally those who are searching for something. So users from search engines have higher click-through rate.