People have started to talk about web 3.0, ever since the term web 2.0 was coined. I've written before how I define web 2.0, and wrote there about my three pillars idea for technological revolution. Let's try to see how web 3.0 is mapped to this idea.
The first pillar is the technological advance. It seems to me that CORS (Cross Origin Resource Sharing) technology is something that can act as this pillar.
Let me discuss this technology a little, as it is a very new and not really known one.
The dynamics of web interactions is evolving, first there was just a plain request-response mechanism in which browser asked for a page following by the server returning it and no more interaction afterwards. That was web 1.0. Then came the Ajax concept, which removed the "no more interaction afterwards" limit. This allowed ongoing interaction between the client and server. This is web 2.0.
Still,there is a limiting issue here, which is the fact that each page/application is talking only to its own server/domain.
Here enters CORS. The combination of CORS and RESTful server-side architecture allows web applications to be launched from one domain, and from that point communicate with any other server from other domains (and bypass the same origin policy of the browsers), and basically allow multi-domain collaboration without the need to interact with the original server/domain (the application's launch server).
The second pillar, the business model, is yet to evolve. But, I believe that we would witness a new kind of collaboration that would yield new kinds of business models. Sites/domains would provide core expertise and not an entire solution. Think of a domain that just provides storage, another that provide's content and a third one that can provide various visualizations / styles for that content, each has its own expertise which eventually results in better product to the user, and where there are better products, there's money.
As for the third pillar, the platform - my guess is that the combination of PaaS / SaaS (platform/software as a service) with the evolving semantic web may act the platform pillar that would allow the web 3.0 revolution.