Web 3.0 is just my shorthand for Web 2.0 plus all the things that enterprises will look forHowever you number the versions, Web 2.0 is bankrupt before they trust what it has to offer, such as viable business models, cast-iron service guarantees and tangible business value. Features like these aren't just a few extra bells and whistles that you bolt on as an afterthought. If they're not there in the foundations, then you have to rip everything down and start over. By the time everything that's required is in place, then I think it certainly is going to feel like a completely new generation of technology, and so it merits a full new version number.
John is right to point out, however, that the notion of service grids, which he and John Seely Brown mooted in a white paper in 2002 (and in other writing around that time) is indeed implicit in my description of the middle layer of Web 3.0, which I called the aggregation services layer. In fact, I think you might fairly argue that aggregation services are the Web 2.0 incarnation of what he and JSB described back in 2002: The missing layer that links the foundation standards and protocols with the application services they enable.
Where I differ from John — as he noted — is in believing that the most value will be generated at the application layer rather than within the service aggregation/service grids layer. John argues that the application services layer will be very fragmented: "I suspect that most application services will address very profitable, but very small, niches." But I think he underestimates the sheer size of this layer, and thus the scope within it for some players to assume very large scale, even while a plethora of others specialize in an almost infinite variety of long-tail opportunities.
At the same time, I think John underestimates the degree of competition and thus fragmentation that will occur in the aggregation services layer— which is why I prefer to call it that rather than use his services grid terminology, with its undertones of utility provision dominated by mega-providers.
The interesting thing about this debate is that either of us could be right — it could easily go either way. Over the next few days I'm going to continue my exploration of what I'll persist in describing as the Web 3.0 landscape, looking at several potential players within these two layers and exploring some of the drivers manifest in those examples that tend towards either fragmentation or concentration of economic opportunity and power.