This seems like a case of correlation not equalling causation. These are probably the people that are more likely to be trusting and sharing both online and off.
That said, people have been sharing for millennia, so are we just now learning to trust each other, and is it because of the internet?
It's about building communities that didn't exist before. That's significant. The modality is the difference. People didn't have a reliable and simple and cheap and instant way to connect. Now they do.
The free exchange of one's property for a value you find acceptable sounds more capitalist than socialist.
Which is odd, because car "sharing" isn't really sharing in any normal sense -- no more than Avis about car sharing or Hilton is about sharing rooms.
More directly to your point, the end of the report (PDF) also addresses the evolving notion of what "sharing" means to people these days.
- it's a Facebook app to utilize the existing trust network
- game elements (gaining karma for sharing)
- built in Python on Google App Engine
I saw the founder speak at the Dumbo Arts fest a couple weeks ago -- it'll be interesting to watch them over the coming months.
