I whipped up a quick hack to give me growl alerts for irssi highlighting. It is pretty horrible, gross, and yucky, but it works well enough for me. I thought I'd share in case people don't care so much about how grotesque this is.
On my server running irssi, I wrote this irssi script:
On my macbook where I get growl messages I wrote this shell script:
...and ran it in cron on my macbook:
* * * * * /path/to/growl-alerts.sh myhost.org