Chris Keene, CEO of ActiveGrid, has an interesting take on the open-source CEO that I hadn't really considered before, but which I think has some validity: open-source CEOs tend to reflect the dynamics of open source, namely they are collaborative and somewhat (somewhat, mind you!) humble.
Open source CEOs don't see every other CEO/company as an enemy in their zero-sum strategy to take over the known software universe. They bring a community-minded approach not just to their technical work but also to their business activities.
You can't take this too far - there are jerks in open source just as there are in the proprietary software world. But I do think there's something to Chris' contention (ironic diction intended). The people I know in the open-source world are fiercely competitive...without being fierce. They are intent on winning without being obnoxious.
All of which makes open source - project or company - an enjoyable place to work.