Python. I wanted to make the underlying ideas as transparent as possible, so I chose a language which many people will find accessible, and I've tried to use simple, easily understandable idioms. I hope it will also be easily accessible to people who use Python rarely.

Translation rights for books in human languages are a well established thing.

I wonder if there's any analogue for technical books using a particular computing language, ie the base explanatory text is kept the same (as much as possible) but the code samples are "translated" to another computer language ?

For example, if I didn't know Python, it would be great to be able to pick up a "translation" of your book with the code written in a similar language such as Ruby.

Obviously, only a subset of tech books could be treated in this fashion, but a way for authors to license their existing content for uses like this would be interesting.

The idea you describe seems like it would also work for learning new languages. If you already understood the subject matter in the book, you could pick up a copy for a different programming language and compare it to the copy in a language you know; comparing examples 1-to-1 would make it significantly easier (in my opinion) to understand the new language's syntax and style, and the applicability of specific features of the new language.

Dr. Andrew Appel (of Standard ML fame) wrote a compiler book, Modern Compiler Implementation in ML, in the way you're suggesting. After the ML version of the book was published, he went back and "translated" it to both C and Java to produce two new books.