It is exactly what you think it is.  The term was brought up in todays demo by Mendeley, which has a product similar to EndNote but with some crowd-sourcing capabilities to categorize content.  You can google the term yourself of course, but here is a good introductory article on “Science 2.0”: http://www.scientificamerican.com/article.cfm?id=science-2-point-0-great-new-tool-or-great-risk