I know one superb jazz portuguese pianist that has never had formal music education, and this shouldn't be a unique case. He learned from listening, transcribing, practicing and playing with others. It's incredible.

Well, I didn't want to get into jazz books, but the "Jazz Piano Book" is indeed the main book I'm following. The most complete, down to earth (in the way it atempts to explain things), although deep book. But I've found another very original book that I highly recommend to those who want an introduction to jazz in "the easy way": http://www.tadleyewing.co.uk/ . It points to the method Scott is sugesting to music learning: the book is constantly sugesting songs to listen and has a terrific "after buy" support with lots of audio material, essential to a good understanding of the book contents. It was a good surprise and the most non-conventional "easy" jazz educational book I've found. Experienced jazz musicians will probably find it too basic, but nevertheless should appreciate the original approach.

The Master Class software I just suggested is also a good alternative to the "book study" approach. Lots of proposed exercises (with the help of midi files, integrated in the software) to practice specific techniques (eg: comping, improvisation, bass lines). It's really great to get new ideas and it should suit those who want to progress quickly without too much theory.

-- José.