I think 2.0 makes a lot of sense.
The basic internet did bring a lot of change. The ability to search and communicate in real-time across the world felt like a momentous change, and I still think it was. So 'basic' is probably the wrong word.
But the new opportunities that web 2.0 provides to collaborate could be even more significant. It can change the way that people work, so enterprise 2.0, knowledge 2.0, HR 2.0 etc all make a lot of sense.
I quite like the analogy to a new release of a software package, because technology is clearly at the heart of the change that we're seeing. And it emphasises that we're looking a very significant change.
But 3.0? I'm starting to see quite a lot of this around, for example in a Melcrum conference next month there's a presentation on Collaboration 3.0: Creating fun and collaborative team experiences to engage employees. I'm not going to go, so I may be being unfair, but there's nothing in the session description to suggest that this is going to refer to a fundamentally different way of operating.
It's all very well to try to show that you're on the leading edge - I do enough of that myself. But I also think it's unhelpful to invent a new name, diluting one that's still emerging, and reducing the likelihood that people will understand either.
OK, if you truly believe in something, fair enough. Most of my readers will live in free countries. I call a lot of what I do human capital management, even though I know most people associate this with measurement or technology, so I risk confusing potential customers of benchmarking firms and software vendors. Tough - the term is important to me and I'm going to continue defining it in my own way.
But web 3.0, collaboration 3.0 etc. I'm not convinced.
See also http://systematichr.com/?p=816.