Unfortunately, I've been too busy really follow the discussion on incarceration that's been going on, but it is a subject in which I am intensely interested. Right now I'm taking an undergrad course at Berkeley on criminal justice and I'd really like to recommend my professor's book. It's called "Crime and Punishment in America," with the subtitle "Why the Solutions to America's Most Stubborn Social Crisis Have Not Worked -- and What Will." The author is Elliott Currie and it's published by Holt, NY. It's a short paperback and it's only about $13. Currie's class is one of the best I've ever taken and the explicit purpose of his book is to debunk conservative theories of crime and criminal justice. It's a recent book (1998) and has up to date stats. He has a whole chapter on "Prison Myths" in which he rips on the "studies" of neocon think tanks like the Council on Crime.
If you want to have the facts and figures on hand to immediately destroy any conservative idiot who says "America is too soft on crime" then this book is a must.
And no, I'm not getting extra credit for this plug.