vincevincevince - 6:43 am on Jul 23, 2007 (gmt 0)

I feel privacy such as this is best handled from the browser. It should be a browser setting which determines how long sites are permitted to keep your personal data.

With each GET request the browser sends, it could send an additional header:
Data-Retention-Until: 2007-12-19T16:39:57-08:00

That way, if I'm only happy for my data to be kept for three days, I can have my browser inform all sites of this automatically as I visit.