I don't know how I missed this, but Robert Birnbaum recently did a fascinating and wide-ranging interview with Michael Lewis.
Some excerpts from Lewis:

This guy Billy Beane is a born Wall Street trader. I have seen this. I worked at Salomon Brothers; I worked on Wall Street. If Billy Beane has been at Salomon Brothers he would be a managing partner. He is excellent at walking into a jungle, seeing the opportunities and seeing the threats, and adapting accordingly. He has wonderful antennae. He knows what you want and he is going to give it to you.
...I've had two interesting institutional responses outside of baseball. One is from the NFL. I gave speech in New York a week before last and someone from the Commissioner's office came and he said this thing is spreading in the NFL. Bill Parcells is giving it out to the Dallas Cowboy's organization. Some guy I never heard of who is the GM of the New York Giants is handing it out to his scouts. I thought, "That's extraordinary." Because the NFL is actually well run. The guy was saying, "The descriptions that you have in the book of the discussions between the scouts and the GM, that was something that died in the NFL thirty years ago. We have become more rigorous the way we think about amateur players and baseball is way behind. The spirit of enterprise is clearly alive in the NFL. People are still looking for a way to get an edge.” The other interesting institutional response has been from Wall Street. The lead investment strategist for Credit Suisse/First Boston, the investment bank, devoted his whole research report a week or two ago to this book. The gist of it was if you want to know how to manage money the Oakland A's are a good example—if you want to look at allocation of resources and how you think about it.
UPDATE: Here is a radio interview with Michael Lewis from NPR. (Hat tip to Mindles H. Dreck.)
MORE UPDATES: The New Yorker has finally put its profile of Bill James online. It describes, among other things, the desire of Theo Epstein and John Henry
to assemble a front office staffed by people who “get it” (shorthand, essentially, for those who can remember the moment they first read a Baseball Abstract).

The literature about Bill James often describes how the narrator or subject describes how he opened the book and was forever transformed - just like a medieval conversion narrative.
Finally (I think), sometime sabermetric ally Thomas Boswell has a decent summary of Moneyball. More to come.