What I also take into account is StackOverflow. There are a lot of programmers who don't even read a page of google search results.
I will also say that from my time on HN, the number of people who read dead-tree technical books versus the number who read ebook versions of technical books may be less than dead even. They're cheaper [new] and services like Safari provide entire libraries at reasonable prices. [I've commented elsewhere in this thread on how Seibel's book exemplifies the some of the Common Lisp community's tone deafness].
What I was getting at is that StackOverflow shows that many programmers in general tend to page fault into learning whatever language they happen to be using. This is a behavior which StackOverflow is explicitly designed to facilitate. It is also designed to facilitate the behavior in ways that are better than traditional Usenet and its web-based descendants in the form of fora.
It is expected that people learn a programming language and when they have actual programming problems, then they come to Stackoverflow.com.
One of the reasons that I listened to all of those podcasts is that I found Spolsky's and Atwood's ideas  about online communities insightful and was able to relate them to my experience in other online communities. I recommend them to anyone who shares my interest.
 and those of their guests and other team members.