] "Every time we checked, some were gone and others had
] moved," said Dellavalle, who is on the faculty at the
] University of Colorado Health Sciences Center. "We
] thought, 'This is an interesting phenomenon itself. We
] should look at this.' "

This is a problem indeed. I imagine Tom, at least, would have some opinions on building the web into a great, big, persistent trust/reputation network. Whats the answer?

On the Web, Research Work Proves Ephemeral (washingtonpost.com)