mod_perl 2.0 now has a new hook: the PerlMapToStorageHandler.
from what I can tell, translation in Apache 2.0 isn't quite the same as it used to be - it looks like the core translate_name phase simply figures out what r->filename ought to be (by overlaying DocumentRoot or various Alias mappings) and the map_to_storage phase actually does the filesystem stat calls to determine the file to serve and things like r->path_info. this is very different from 1.0, where the stat calls could be overridden with a PerlTransHandler.
so, the bad news is that returning OK from a PerlTransHandler will not reduce IO overhead for dynamic URLs. The good news is that now you can use a PerlMapToStorageHandler for that. and while I'm still trying to figure it all out, it seems that the canonical use for each will remove the separation of functionality required in 1.0. That is, the PerlTransHandler can be used to safely meddle with $r->filename, return OK, and still let Apache's core mapping engine serve the right file. cool.
