I hadn't heard of them before, but they publish a bunch of books for use 
with "Open Source" software programs:

http://www.packtpub.com/books/all/open-source

I learned about it from the posting below about their new Octave book.

Mike


---------- Forwarded message ----------
Date: Thu, 23 Jun 2011 10:10:36
From: Jordi Gutiérrez Hermoso <jordigh at octave.org>
To: Octave Maintainers List <octave-maintainers at octave.org>,
      Octave-help <help-octave at octave.org>
Subject: New Octave for Beginners book

Allow me to advertise this book:

       http://www.packtpub.com/news/become-confident-octave-user-packt%E2%80%99s-latest-book

It's a book intended for absolute Octave beginners. I had the distinct
pleasure of being a technical reviewer for the book, and heartily
recommend it to students and practitioners alike who want a gentle
introduction to Octave. The book begins with the very basics, from
installing Octave and elementary flow control operations to more
sophisticated applications like numerical solutions of elliptic PDEs,
statistical description of data, and Fourier analysis of signals. It
also covers more advanced programming topics such as how to create
standalone C++ applications with mkoctfile or how to prepare
Octave-Forge packages. I myself learned a thing or two about Octave as
I was reviewing this book.

If you or someone you know would like a printed guide on Octave beyond
what Octave's own documentation can offer, consider this book.

- Jordi G. H.
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