Interesting article on Boing Boing about Google image labeler and how to entice the mass into a dull job by the means of a game challenge...
It's a clever way to do retrospective tagging. Organizations with large archives of data are likely to do more of this in order to open access to their "long tail".
In a non-digital world, an analogy could be the way the BBC organized national "treasure hunts" to retrieve long missing archive material, except they were one-offs.
Google has found a way to harness the power of the mass (and no, this has nothing to do with what happens to humans in the Matrix trilogy, although ...)