I did stick in ad_return_exception_template into the tree some time ago ...
For use of it to happen in 4.6 we need someone to step up to the plate and volunteer to do it within the next couple of weeks. Janine will be managing the 4.6 release process so if you can commit, get in touch.
Bruno Mattarollo also figured out how to template the 404 page returned by the request processor. He's back from holiday tomorrow, Jon's interested in the same thing, and maybe they can get put their heads together and get this in 4.6, too? Jon?
If not both of these things should be in 4.7 for sure.
