I don't think Willem Buiter got things right on his post today in the FT. The IBM monopoly ended because of competition from minicomputers in the 70s, workstations in the 80s, and microcomputers in the 90s (respectively DEC, Sun, Microsoft among others). Antitrust regulation had very little to do with it. The Microsoft monopoly is finishing now because of the iPhone, netbooks, and all the web apps. Microsoft has become irrelevant because they are not technological leaders, not because of action by European competition authorities. And I believe Apple flourished when Steve Jobs and his NeXTies were forced to find ways to compete under Microsoft's radar screen, developing the NeXTStep (aka Mac OS X), the iPod, and the iPhone way past what fat and slow corporations were able to.
He may be off in his analysis of Google as well. I used to think that privacy by data overflow was possible. Google and the Great Firewall of China showed it is not. There is no anonimity in the mass of information on the web, and no technological route to privacy. Competition authorities tinkering with cookies will not do, we need to draw a line after which invasion of privacy becomes a criminal offense. The only hope for individual privacy is strong protection from a liberal government. I think that Buiter is close to the right conclusion - that we need strong laws guaranteeing individual freedom - but he arrived there by a tortuous route.