A good explanation of what the implications are of page views vs time spent

The marketing world and the blogosphere have been churning of late over the news that Nielsen is no longer counting page views and is now counting time spent on web sites in their overall rankings. There's a great analysis piece here.
In some ways, Nielsen is affirming a metric I've been touting for years -- cost per minute spent with prospect. (also cost per minute spent with eyeball)  --  as a way to judge the value of long content-rich exposure like speeches, customer events, and sponsorships vs the 30 second ad.
The problem comes when you try to compare the impact of on-line media, CGM and traditional media. If MSM is still counting eyeballs, and on-line is counting time, and CGM is counting influence, what's a measurement maven to do?  Since its not likely that there will be one metric anytime soon, the answer is, keep them all separate and measure against your competition instead.