Jon Udell writes:
The current craze for tagging things — Flickr photos, del.icio.us, and Furl URLs — shows that people are more likely than you’d guess to add structure to content. Under what conditions will they make the effort? First, tagging must be easy — a two-second no-brainer. Second, it must deliver both instant gratification and longer-term value to the person doing the tagging. Third and most important, it must occur in a shared context so that network effects can kick in.
Of course, some tags are implicitly woven into the fabric of our content. Consider, for example, the recent Demo conference in Scottsdale, Ariz. As information about the event flowed into the blogosphere, a likely tag to hang on conference-related items would have been the distinctive name Demo@15. And sure enough, that tag was used on both Flickr and del.icio.us, although by only one person. (Hint to conference planners: If you want the blogosphere to synchronize its coverage of your event, pick a tag and promote it.)