InfoWorld: Collaborative knowledge gardening.
Jon Udell. To CTOs, though, I'd say that both are collaborative systems
for building a shared database of items, developing a metadata
vocabulary about the items, performing metadata-driven queries, and
monitoring change in areas of interest. In the case of Flickr, an item
is a photo; in the case of del.icio.us, it's a URL. [Tomalak's Realm]