Apply new SafeCache patch
One of Dan Boneh's students just upgraded SafeCache to Firefox 4. He also implemented a headers-only version of the double-key cookie policy: http://crypto.stanford.edu/cs294s/projects/browser.html
While the cookie bits don't seem to be that great (lots more side effects compared to Dan Witte's policy), the SafeCache definitely seems useful. I should merge them both in and just disable the cookie bits via pref.