David Weinberger, on his JOHO (Journal of the Hyperlinked Organization), examines the need to have an open, and persisting service that maintains a namespace for tags created for each blog post. Currently, he is linking his tags to Technorati, but he said he did this because he assumed that this was necessary in order to have his tags picked up by them. It is possible to have your tags link to Wikipedia or to your own Web site.
One commenter also provides the correct code for linking to Wikipedia.
David, any chance there'll be a Taggercon any time soon?