Another beta book

Last year I bought the Pragmatic Programmer's book, "Agile Web Development with Rails" by Dave Thomas and David Heinemeier Hansson. The Pragmatic Programmers have the cool method of allowing the purchase of their books before they're finished, in which case you get access to the latest 'beta' version of the book as PDF. This is a great way for people to get at the essentials of a book they're waiting for as long as they can look beyond the odd rough edge that has yet to be ironed out before the book goes to print. It also must generate a reasonable amount of extra income for PP, as they charge extra for the beta book service (fair enough). Anyway, the Agile Web Development book has been great for me recently as I've finally got around to tackling Ruby and Rails, so when browsing the Rails website and I noticed another book from the Pragmatic Programmers on Rails, I thought I'd check it out. It's still 'in beta', but I've gone for the beta/hardcopy combo and am waiting for my download to be available of the beta as the book looks a very handy follow-on from the Agile book, despite being a different author. The new book covers more advanced techniques than the 'Agile' book and will hopefully become just as handy.