MIT Tech Review has an interesting article about how Linux could overthrow Microsoft. But personally, I don't think that will happen. Windows will always be popular, it just won't be a monopoly any longer. And this is a bit too optimistic:
With some improvements, the open-source model could even become the dominant global production model for software. If it does, it will be an irony. The open-source movement was launched 20 years ago by an antiestablishment technologist and for years was ridiculed by the mainstream computer industry. But it quietly drew more adherents every year, spreading first among iconoclastic hackers because its legal structure and culture offered them freedom from "the suits"–that is, the entire managerial, financial, and legal apparatus of the commercial technology sector. But now IBM, Hewlett-Packard, and Intel have become supporters of Linux and open-source development. Their goal is to reduce Microsoft"s prices and power by commoditizing mass-market software.
I mean, I'm all for open source but, come on, the dominant model? I think it will be different. I think we will see the emergence of a pseudo-open-source model built using "wisdom of the crowds" type stuff, but where people are paid for their contributions. And not just software – all work is going to become more distributed.