This seems like such an obvious problem that I suspect I must have something wrong in my set up so I am hesitant to report a bug to bugzilla. Can anyone else confirm this problem exists? Javascript files are not cached by NN6/Moz0.8 - all other file types (apart from a few random image files) are cached and I have checked the headers as far as I can and the expiry date is set 1 month in the future. Any takers?