As reported by Remco Nabuurs. Jetspeed sets the following HTTP response headers by default:
Cache-Control: no-store, no-cache, private
To force a round trip in IE when pressing the BACK button, the expires header needs to be set to -1. Firefox and Safari assign a higher priority to the expires header and perform a round trip. When an application makes use of Ajax calls in-between requests, and an application architecture is adhered (the Ajax calls change server state), this leads to pages with out-of-sync data.