Explicit Ownership Declaration
"Unlike on Web 1.0, Web 2.0 resources are always specified with explicit declarations of their ownership. On Web 2.0, we know exactly the person who specified the tag, who adopted the widget, or who made the comment. This ownership declaration over any piece of Web-2.0 resources is explicit and unambiguous. In comparison, the same type of ownership declarations over Web-1.0 resources is generally implicit and often specified in anonymous ways, and thus many times it is ambiguous to precisely determine the ownerships (since the owners themselves may leave no identities).
There is a reason why on Web 2.0 the explicit declaration of user ownership becomes essential." (http://yihongs-research.blogspot.com/2008/02/resource-portability-path-towards-next.html)