The Ruby on Rails Tutorial: Learn Rails by Example (a.k.a. railstutorial.org) by Michael Hartl has become a must read for developers learning how to build Rails apps. Michael has put together a great Rails 2.3 tutorial, releasing it all for free online chapter by chapter. Now, Michael's going three steps further:

1 — A new, Rails 3.0 focused version. The free online book previously covered Rails 2.3 but Michael's updated it to cover Rails 3.0 too. He's also selling it as a DRM-free PDF for $39 (you get a PDF of the Rails 2.3 version too). As a gesture of goodwill to Ruby Inside's readers, he's made a coupon code that works till the end of August - it's rubyinside01 and gets you 20% off (so a total of $31.20 in the end).

2 — Creative Commons licensing of the existing online text. Like all of us, Michael needs to make some money, but a side benefit is that he's making the existing Rails 2.3 focused text Creative Commons licensed! This will allow you to distribute it, translate it, put snippets on your blog, and so forth. (Update: Michael notes that this is sort of in the air at the moment pending more resources. He has more preparation to do to make this work properly, but the spirit is there.)

3 — A print book, published by Addison-Wesley. A print edition, Ruby on Rails 3 Tutorial: Learn Rails by Example, is due out in the fall as part of the Professional Ruby Series (the same series as The Rails 3 Way by Obie Fernandez), and is currently available for pre-order at Amazon.

As a bit of a "geek aside", the Ruby on Rails Tutorial book is written using PolyTeXnic, a pure-Ruby markup system built on top of the LaTeX typesetting system. PolyTeXnic converts a select subset of LaTeX to HTML, while also producing PDFs via the pdflatex command.

In addition to supporting code-heavy programming books such as Ruby on Rails Tutorial, PolyTeXnic can also produce mathematical documents; see, for example, Michael Hartl's anti-pi propaganda piece called The Tau Manifesto. Michael hopes to release PolyTeXnic as an open-source project some time later this year. I keep nagging him about it.