Business 2.0 has nice introductory write-up to the whole “Web 2.0” trend: How To Become The Next Microsoft.
In my oh-so-humble opinion, I think the whole “Web OS” concept is a bunch of hooey. It’s one of those ideas that fits so nicely in the brain, it’s got to be right, but in reality the world is a lot more complicated (sort of like…Communism).