The University of Michigan has introduced a social bookmarking application, MTagger. Here is Ken Varnum:
More important than the tagging functionality itself is what MTagger will allow our faculty, staff, and students to do. MTagger brings a social component to research that we have not previously had. It will allow users to share knowledge about library resources with each other, to enable quick-and-dirty subject guides to be produced, and -- we hope -- to bring researchers together via their individual tag clouds. As research moves online, chance meetings in the stacks of researchers with overlapping interests become even more rare. Through tagging, we hope to be able to recreate some of those synergistic interactions as one researcher finds a tag of interest, and through that, the other researcher. [New Tagging Tool at University of Michigan Library (RSS4Lib)]
I very much like the way Ken describes the rationale for this initiative above, and the focus on social connection rather than retrieval. Scale and incentives are important for this type of behavior: it will be interesting to see how well they do.