A cursory search of CPAN for PGP related modules turned up - Crypt::OpenPGP, Crypt::PGPSimple and Mail::IspMailGate::Filter::PGP.

A bit of google-whoring also turned up this little gem which may be of use to you.

 

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'