My most comprehensive article on the issues is:
Much more for the curious at:
At FLOSS Manuals (http://flossmanuals.net/), where I volunteer, we're filling the gap with well-organized writing projects combining peer review from the public with experts from various free software packages. There's a very active mailing list and a lot of highly praised output on the web site.
(I may go back to one of the articles cited in the posting and add this comment to it.)
The difference between a career and a job is about 20 hours a week.