I feel compelled to say something here. I don't know that I'll be heard over the din, but so be it.

Stallman and Gates stand at two ends of a particular spectrum. The fundamental question is about what rights the users of a piece of software should have. On Gate's end the belief is that the users' right is simply to use the software. Stallman's belief is that the users' right is to use, redistribute, and modify that software. Modern copyright law falls in line with the proprietary side. The GPL is a hack leveraging that same law to guarantee that the users of software governed by it, or software derived from the same, retain the rights of use, distribution, and modification so long as they also abide by the GPL under which they recieved that software. The key point of the GPL is that it restricts recipients of the software from distributing derived works under licenses which restrict the rights of the users more than does the GPL. That is the key point of contention. It is a recursive conditional grant of license dependent upon propagating those rights with derived works.

The key point of proprietary software is that the copyright holder retains the exclusive rights of distribution and creation of derivative works. Copyright law grants broad powers to the author to restrict recipients of software from redistributing it or deriving new software from it. That's the mechanism by which copyright law operates. The intention of the law is to create a framework which encourages the creation of new works by securing those exclusive rights to the author. That exclusivity is not a natural right, but is a statutory one granted by Congress under the powers given it in the Constitution. Developers of proprietary software generally use those rights to ensure that they recieve payment in exchange for the use of the software. Developers of software released under the GPL use those exclusive rights to ensure that all future users of their software retain those same rights.

Disagreement over what the rights of the author are and what are the rights of the user generates the friction on this Gates <-> Stallman continuum. Most people fall somewhere in-between those two extremes. Stallman believes that it is a moral imperative to ensure that all users everywhere retain what he sees as fundamental rights. Gates believes that it is imperative that the authors retain the power to define what rights they grant to the users.

Is Stallman extreme? Absolutely. Is Gates extreme? Absolutely. But both of them are self-consistent and stand as useful measuring sticks by which to measure different approaches to copyright. Stallman may be an ass, but he's an extremely principled one. Gates may be a robber baron, but he exemplifies the power which is wielded via exclusive copyrights, and he stands to do a great amount of good in his philanthropical efforts. Both of them are talented technical minds who have pursued their goals passionately. Both of them have had a huge impact on the modern software landscape. Which of them is right? Personally I think that one needs to measure the results of their efforts to decide. And that's a very subjective and touchy subject which I won't go into here. You'll have to decide for yourself what approach is right for you as a developer of software. I think it's great that the choice is there to make.

Please note that all I'm writing about now is philosophy. I'm not going to touch practical implications yet.

If I have made a factual error, please respond and correct me.