I was thinking about the news that was going around last month about yahoo making its data retention period shorter (with exceptions to let them get away with whatever they want, but that's par for the course). e.g. http://www.theregister.co.uk/2008/12/17/yahoo_anonymization_explained/ It seems like a good idea to set the search_url default to whoever is the...let's say "least bad" in terms of privacy at a given time.