How to install Perl on the Iphone:

UPDATE: Now easier (tested and working on the 4.0.1 OS)

- copy this file to your Ipod/Iphone filesystem via SFP: http://coredev.nl/cydia/coredev.pub
- execute "apt-key add coredev.pub" at the same directory
- execute "echo 'deb http://coredev.nl/cydia iphone main' > /etc/apt/sources.list.d/coredev.nl.list" to add the new source
- Open Cydia and install Perl.

Have fun