This document was writted using LaTeX (http://www.latex-project.org/). The documents use macros written for documenting the Python (http://www.python.org) language and Python packages. Generating the PDF version of the document is simply a matter of using the pdflatex command. Generating the HTML version of the document, of course, uses plasTeX.
The wonderful thing about the HTML version is that it was generated from the LaTeX source and Python style files without customization1! In fact, in its current state, plasTeX can generate the HTML versions of the Python documentation found on their website, http://www.python.org/doc/. Without customization of plasTeX, the only remaining issues are that the module index is missing and there are some formatting differences. Not bad, considering plasTeX is doing actually expanding the LaTeX document natively.