The degree to which readers engage with media should be a critical factor in understanding the value of that media. My view has been that the degree to which actions intended from any marketing activity - say downloads - occur is proportional to participation in that media by readers/ views/ the community. For this reason I like Scoble's idea on measuring media engagement.
This will require a step-change in thinking by communicators. Rather than looking at the reach of publications, we need to think in terms of participation.
Illuminating Buzz's experience in downloads driven by USA Today vs. Scoble is our experience with online tech media. From them, the traffic is nominal. But a post by James Governor of Redmonk referring to LogLogic on average drives a 14% spike in traffic to the site. This is just one dimension of participation and probably the most base level (traffic, link push-through, etc.).
Where Scoble starts going with this idea is really interesting and where you get to the heart of participation. Do people not only scoot from James to us but when they arrive do they start doing things - like downloading, viewing, registering, commenting? That is where traffic becomes exponentially available.
So which is more valuable to me. InfoWorld or Monkchips? The lazy answer is both. But in resource constrained start-ups you punt on the media driving hardcore participation.