They kind of proved this from the day one. Interesting documentary on this topic is Revolution OS[1]. It is kind of biased and now very outdated but it is still worth watching. If you haven't seen it and you are interested in early history of OSS I recommend it.

1. http://www.imdb.com/title/tt0308808/

cool,thanks.I'm not aware this documentary.Will watch it soon :)

Red Hat proved that one company can make money using the support business model, but it doesn't look very replicable.