It's not Perl, and it doesn't do Postscript day-at-a-glance pages out of the box, but you might want to check out remind. This is what I use, but I get along fine with the monthly calendar (Postscript, HTML, and plaintext) and the plain-text daily view.

Since it does have code for generating Postscript monthly calendars, you might be able to adapt it to generate a daily view. On a more Perlish front, parsing the output of "remind -s" and using PostScript::Simple to generate your daily view might be more appropriate.

For some more detailed articles, see http://www.43folders.com/2005/02/guest_mike_harr.html or http://www.linuxjournal.com/article/3529.