I ran a d-u on 64-bit today. Only a couple of problems. First, I let it remove pdftk (not sure that it's due to a perl dependency or not). Hope it gets fixed soon.
The second problem is with spamassassin 3.3.1. Under perl5.12 a line in Check.pm causes a warning. This causes a glitch in retrieving mail and you get the same message retrieved over and over. You also get a lot of email about the failure in the fetch process. The error is
warn: Use of "goto" to jump into a construct is deprecated at
/usr/share/perl5/Mail/SpamAssassin/Plugin/Check.pm line 409.
Fedora encountered this problem last fall when they were pushing out perl5.12. They are using spamassassin 3.3.2 from SVN. I tried simply copying the Check.pm file from that version, but it generates other errors.