There is a fascinating interview with Richard Stallman on LinuxInsider called GNU GPL Creator Richard Stallman on the Meaning of 'Free.'
Now you may think Free means, well free, but as Stallman says, free is more a state of mind as in free speech, rather than "free beer." He outlines the four tenants of software freedom and goes onto to discuss the differences between "free software" and "open source," a term and movement he sees as a bastardization of the free software movement, and takes a stab at Microsoft and other for-profit software companies.
It makes for fascinating reading and provides a history of free and open source software of which I certainly had little knowledge or understanding. A highly recommended read; this guy is as consistent in his beliefs (in a good way) as anyone you'll come across.