Tim Bray, referring to a French report on the open-source threat to Microsoft, quotes the authors as explaining the appeal of open-source software to developers as "je donne donc je suis" -- "I give, therefore I am" -- or, I might add (mimicking the Latin of Descartes), "dono ergo sum".
Over the years I've had a hard time describing to my capitalist friends why I am so active in the open-source community (specifically Jabber) -- when I tell them it's a communalistic meritocracy, they look at me funny. Certainly lots of folks love open-source software because it is free as in beer; after all, who likes to part with their hard-earned cash? But what's in it for those who produce all this free stuff? Those of a libertarian persuasion like to quote Heinlein's dictum TANSTAAFL ("there ain't no such thing as a free lunch"); granting the truth of that statement makes it even less comprehensible why people would volunteer to cook the lunch for others to enjoy!
But people do. And not just starry-eyed communalists -- even long-time capitalists like me are active in the open-source world, often spending nights and weekends working to make things that we give away. Eric Raymond's anthropological musings have revealed that open-source is a gift culture, and that the members thereof compete with regard to the quality of what they share.
But I think it's more than that. Speaking only for myself, I got involved with Jabber because I felt it was community to which I could productively contribute and thereby give something back. Yes, we're talking about guilt -- I felt more than a bit guilty about taking all that Linux goodness for free without contributing anything in return. So I started giving. Not to compete or show how smart I was, but because I wanted to join in the fun and convince other people that Jabber was cool. I wanted to help Jabber succeed (this was late 1999 and early 2000 -- we needed a lot of help back then, believe me!).
Since I'm not the world's greatest coder, I started out writing documentation and eventually began documenting and developing Jabber protocols (in fact lots and lots of protocols), which provide the central focus in the Jabber world. Eventually it seems that I became the de facto leader of the Jabber community, which is an odd position for a moderate anarchist to be in, since every fiber of my being resists the temptation to give orders and tell people what to do.
When I started out in the open-source world as a mere Linux user (in 1998 or so), I really was a true capitalist pig of the Randian variety ("big business is America's persecuted minority" and all that). However, as I slowly became a more active contributor, I found myself living the classic Stoic metaphor of the circle of concern: Jabber people and Jabber technologies became important to me for their own sake, and their well-being became part of my well-being. Thus a corporate capitalist was transformed into an open-source communalist. It's funny how life goes sometimes...