Electronic distribution of tutorial/learning material is important, it can be included with the distro or be easliy downloaded from the website. However, deadtree versions are important too - often its easier to read/more portable than on screen and how many of the potential market are going to have access to Kindle type devices for away-from-the PC study?
I'd suggest getting a magazine producer interested in the concept - a special edition of a magazine format publication, for example the specials produced by Linux Format (Future Press) in the UK or even the A6 feature booklets (they did one on PHP with issue 135 of LXF) produced to accompany the magazine might be a way forward.
Anyone remember Babani Press? (www.babanibooks.com
) They do pocket sized technical manuals very cheaply, 10 quid or less. If a pdf manual is available, it should be easily converted to such a book.
I'm just a bouncer, splatterers do it with more force.....