Are key open source developers volunteer developers ?

Key people in Linux development are paid developers.  Actually this was the reason why Linux became most popular GNU-based kernel -- distributors hired most of open source developers and convert them into paid developers.  Some developers became cofounders of Linux companies, some highly paid employees of this companies. In reality Linux companies staff listings look like a roster of open source developers. That means that considerable part of open source software  is not "donated", but "taxpayer-funded" (university-funded) or "commercially funded" (current versions of Linux).

Even Linus Torvalds cannot be called volunteer after probably just first two years of kernel development: after that his "hobby" was financed by the University of Helsinki (which allowed Linus to do development on his university job), then Transmeta picked the bills.

Later IPO stock gold rush remunerated him quite nicely, probably on the level the few leading commercial Unix  developers enjoy. I would say that Linus Torvalds probably belongs to the first dozen of most highly paid developers in the Unix word.  Without commercial developers and support of  development by commercial distributors Linux in its present form would be impossible. Most significant open source products are now developed by mixture of people with a rather high percentage of paid developers (staff of Linux companies) and in this respect are not that different from commercial products. It's just new commercial software development paradigm that in my second paper I called complexity-level based commercialization.  Actually FSF from the beginning used paid developers to develop software  and Linus Torvalds after the initial two years or so became a paid (by the University if Helsinki) professional developer. That means that CatB's claim that Linus Torvalds is a volunteer developer contradicts Linus Torvalds biography. For example it looks like the decision to include SMP into the kernel was commercially dictated, including so called "valuable considerations". In the paper Lawyers Guns and Money - KDE and Corel Working in the Real World  by Dennis E. Powell described this phenomenon in the following way:

The dominant view is that this is generally a good thing.

And it can be. But it can also become a bad thing, and unless some lines are drawn, it's a sure bet that it will.

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Even uglier, one could imagine--and this example is entirely hypothetical--a situation where the top people in a development effort accepted what lawyers call "valuable considerations" in exchange for looking the other way as a project got steered in a way that benefits a particular company. Nothing illegal about it.

Less sinister but troublesome nonetheless is the simple culture clash when open source meets commercial software. Corporations play it close to the vest, open source does anything but. The place where they meet can be awkward and frictional--it's hard to imagine them being otherwise. The potential for abuse is real as well. Indeed, Jon "Maddog" Hall of Linux International has done and is doing much to educate corporations about a crucial reality: they don't own the system and they cannot mandate changes in it. He has helped many companies understand the differences between closed, proprietary software and open source.

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The leading voice of open source is Eric S. Raymond, again one of the few in the Linux community recognized just by his initials. ESR is watching more and more corporations become involved; his philosophy embraces the idea that closed development is old and creaky, while open source development is young and robust. A company will do it the new way or die:

"I'm not worried. What I see is corporations realizing that if they want our results, they have to buy into our process--and if they don't, they'll be eaten by a competitor who does."

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I don't know of any lawyers who would be eager to try to defend the GPL if offense came to judge and jury. Commercial software companies have over the last decade tended to give the best parking spaces not to programmers but to lawyers. It would take some heavy-duty mobilization to take on a big software company and not die of attrition before a dispute ever came to trial. I think there will be offenses, as surely as there will be another VBX macro virus.

It's frightening, the idea that Linux and its applications could fall victim to its own success. But wherever there's money, big money as there is now in Linux, there is someone very clever who will try to take it away.

Corporations and open-source development are for the most part diametrically opposed as to organization and goals. Neither is bad; indeed, neither is better and both can be abused. But when the two come together, it's oil and vinegar--it needs a little shaking up before it can go onto the salad. And these are indeed the salad days of Linux.

It's not difficult at all, though, to imagine the companies that make commercial software for other platforms looking upon Linux as some kind of odd little brother. And, with a smile, saying, "I'm very idealistic. I want to make the world a better place for me to live in."

The paper also contains a very nice quote from old Peanuts cartoon that catch the essence of the problem "I'm very idealistic. I want to make the world a better place for me to live in."