I recently upgraded to the latest CPAN.pm, and I noticed a difference in behavior - when updating a module that's part of the core, it updates the copy in /System/Library/Perl instead of installing a new copy in /Library/Perl.
I noticed that CPANPLUS did this for me, too, with Perl 5.8.0 in /usr/local. It installed Attribute::Handlers in /usr/local/lib/perl5/site_perl/5.8.0 but left the copy in /usr/local/lib/perl5/5.8.0 (core).
This leads me to think that this is typical and expected behavior.
David
-- David Wheeler AIM: dwTheory [EMAIL PROTECTED] ICQ: 15726394 Yahoo!: dew7e Jabber: [EMAIL PROTECTED] Kineticode. Setting knowledge in motion.[sm]