Social Tagging, or bookmarking, develops over time a folksonomy (as opposed to more rigid corporate taxonomies). LibraryThing, for example, successfully exploits this concept in the realm of books, to the delight of their users.
Recently, it seems that social bookmarking made it in the world of mainstream libraries: have a look at this library item in the online catalog of the Penn Library. They also have LiveChat support. That rocks! Thanks to "UPenn Catalog Tagging" by Steven M. Cohen for reporting this.
I strongly believe in the usefulness of social bookmarking in the enterprise context. Hopefully, we will see in the coming year an increasing number of examples where mainstream institutions are embracing enterprise bookmarking.