I got my list of what's in the core from http://www.perldoc.com/perl5.8.0/lib.html, which, to me, implies what's supposed to be in the core for 5.8.x. I checked my copy of 5.8.2 and it includes files not on that list (as well as not having files on that list). Files not on that list that I wouldn't think should be in the core include:

• Filter::Simple (is it used by other core modules?)
• Hash::Util (same criteria as Scalar::Util and List::Util)
• Storable and FileCache
• Getopt:: (Is it used by some Makefile.PL's?)
• MIME::
• Digest::MD5 (unless it's needed by CPAN)
• Data::Dumper (this is borderline, IMHO)
• User::

The dbmopen support in perl5 ... Personally, I think that dbmopen and friends should be treated as locked is with Threads. If you use the module, you get the keyword, otherwise it's not reserved. I think that would be an acceptable compromise, but, then again, I've never used (or seen used) dbmopen and friends in my experience.

I would suggest an additional cleanup activity - removal of all reserved words that require an additional module to work. locked() isn't a reserved word in the core ...