This is an interesting article from Mute magazine. I read it at the film to start.
http://www.metamute.org/en/InfoEnclosure-2.0
Basically it claims that Web 2.0 resources such as flickr are purely ways for us to provide resources for capitalists to make money. The authors make interesting points about why sites such as flickr and YouTube have taken off, wheras P2P applications have been demonised as being solely for copyright violation. They certainly made me think that I should be using P2P a bit more, and perhaps distributing the videos and images that I make that way instead. I think I will start a torrent tracker on my server now, and do some of that, but they do miss out on the major point of many of these sites.
I use flickr and vimeo a lot so I will use them as an example. A common misconception is that flickr is primarily a social networking site. Personally, the thing I like most about it is that it is a secure place online where I can archive my photos. The fact that other people can browse them, and even download them and avail of the creative commons license under which I publish them is just a bonus. I could make all my photos private, so that only I could access them. There would be no social component at all. I would still find this a very useful tool.
So instead of hosting my photos privately on flickr, I could create a torrent and send them to people that way. The problem here is that there is no guarantee that this content will be archived in the same way. In fact, in all likelihood, nobody will download the files from my personal computer, and when its hard-drive dies, all will be lost. P2P is amazing, but its amazingness decreases rapidly as the popularity of the thing being distributed decreases. This is why it is perfect for distributing the latest hollywood movie that everyone wants to see. It's not really a great alternative to a dedicated database which doesn't care about the popularity of your content.