On Jun 4, 5:55  
> > I'd say wiki - if it's in Markdown or Textile, it could be easy enough to
> > wget everything and make it an acceptable PDF/ e-book style file every now
> > and then?
>
> Not really. They're quite distinct styles. An offline wiki is trivial,
> certainly, but it won't have the structure and coherency of a book.

+1 for wiki

With the wiki data (e.g; in Markdown format) you could manually
build (impose) the structure of the book, then use ruby to process
the different chapter from the markdown to any other format
(i.e. via LaTeX or ConTeXt).

The advantages are:
- produce high quality pdf document (thank to TeX),
- allow to automatically produce other output format
  (immediate html output),
- allow to let someone else translate the book to foreign languages

For sample, the jelix book (a php framework) is automatically
generated to pdf from a dokuwiki to xml docbook, then LaTeX.
the pdf.

    http://download.jelix.org/jelix/documentation/en

-- Maurice