You probably already know about (or write) the Perl client implementations in development and located around this directory.
I just added a file to this directory called cf. It's a script that notifies you when any of your friends has updated their journal. There's no GUI yet like LJUpdate that was recently posted in lj_dev, but it's functional and a decent demonstration of LiveJournal.pm. Let me know if you have any problems with it. I just whipped it up today after reading about the windows one.