From a quick survey of my machine, I got this list:
Extensions:

*.pod
*.pot
*.la
*.po
*.ix
*.a
*.so
*.bs
[download]

Files:

autosplit.ix
LICENSE
SIGNATURE
AUTHORS
ChangeLog / CHANGES
CREDITS
[download]

How should it work? Will you propose something along the line of MANIFEST but for installed modules? Something that could be useful to uninstall packages? I haven't any experience on the behind the scene of Perl modules, I just got a CPAN id (btw, approved by you!). Any explanation will be welcome. update: added some files and corrected a typo.