Enterprise 2.0 - what's behind the buzz?

I recently heard the buzzword Enterprise 2.0 for the first time, without really understanding what it means. If it's only about figuring out what Web 2.0 means for the business world - such as Web 2.0 tools in intranets - why do we need a new term for this? Or is it just a new term for computer supported cooperative work (CSCW)? Or is it CSCW + inference mechanisms? If the latter applies, maybe it is interesting to think of mechanisms how to integrate folksonomies, ontology management and collaborative filtering. On the other hand, I'm still unsure about collaborative content sharing - why should anyone give away their knowledge for free without knowing what they get in return?