Diigo is about "Social Annotation", a superset of social bookmarking. We believe that the social annotation service provided by Diigo can really enhance your experience for online browsing and interactions, and for information gathering and sharing.
Microsoft's bloggin, photo, social something. Seems pretty dead to me - it's online since september 2003, see also http://www.wired.com/news/culture/0,1284,61095,00.html