You can tell Perforce to automatically mark certain files as type 'ktext', which is necessary to expand the RCS-like keywords. Unfortunately you have to do this on a per-depot basis and I forget to do so when creating/using a new one. So this post is to remember two things:
This perl script will invoke the 'p4' command-line client to modify the filetype for those file extensions you specify. The only requirement is IPC::Run, which at least on ActivePerl is there by default.
 Technically you don't have to (you can use the '//...' depot map) but if you're working in an org with many different development groups, some of which don't have much contact with one another, it's pretty rude to create a global type map.