Thanks! Glad you like it. As you probably know, there's already a Rails Tutorial chapter (and screencast) on Rails 3.1, but I'm also working on a full 3.1 update as well. Look for the new book in November or December, with the screencasts to follow a couple of months later. Sign up for the news feed for the latest updates: http://feeds.feedburner.com/railstutorial
The supplementary Rails 3.1 chapter and screencast were free for existing customers. The full revision won't be free, but existing customers will receive a substantial discount on the new product.
As far as my publication and production processes go, I have big plans in this direction. I need to make the 3.1 update first, but after that I'll have more details for you. Stay tuned. :-)
I wrote a book called "Rails 3 in Action" for getting started with Rails. Obligatory link: http://manning.com/katz
The idea behind it was to have more focus on BDD than anything else out there, which is exactly what the community is all about these days.
Just like Michael's brilliant book, we go through building an application from the ground up using Rails 3.1, RSpec, Cucumber and many other gems provided by the community.
Ruby on Rails Tutorial is awesome. Even though I went through most of the Agile book years ago, going through the Tutorial helped me: get up to speed with newer versions of Rails, learn the basics of git, and see how test-driven development is done.