I have looked at the Perl in PostgreSQL and it works fine. I have not used it in production only because I didn't have a need for those type of imbedded procedures. Where it would be useful would be where you wanted to work with some data as a procedure within the database so that whatever its triggered it the code gets run. Where I see perl excelling is in reformatting some text, or do something which plays to perl's strengths.

One Pg/SQL example I saw was changing some text, 'CONFIDENTIAL', into 'C O N F I D E N T I A L' and it was pretty cumbersome in Pg/SQL compared to a 1 liner in the embedded Perl so that's the type of place I see for the Perl interpreter inside PostgreSQL.

#basically this type of effect
my $var=join(' ',split('','CONFIDENTIAL'));
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I rebuilt Perl into a shared library version to link it into Pg.