Ha! As it happens I'm actually working on cron in Perl for PPT. I was planning on posting it to perlmonks when done to ask for comments and optimizations... A functional but not yet fully complete version is here:

http://web.mit.edu/belg4mit/Public/cron UPDATE: it now lives at: http://pthbb.org/software/crond/

Of particular interest are the non-standard options -f and -X

-f allows you to specify a crontab in a non-standard location

Stuff to do: security (setuid and setgid) checking crontab update times and reloading as necessary

internal mailer (would be perfect for this, just set the crontab entry to cat a file...) some other odds and ends