I haven't experimented with it, but perlfilter discusses this.

Update - did a super search

Here are a few relevant nodes:

• Source Filters
• Hiding your Script
• obfuscating source code
• Concealing Perl Code
• simple encryption for perl files
• Protect source code
• Perl Obsfucate Or Encrypter
• Closing Perl Source
• Here is a commercial obfuscator
• perl2exe - no more secrets
• Protecting perl source code