tell application "iCal"
activate
quit
end telland saved it as an app in my applications folder as 'dockiCal.app'. Then I added this line to the end of my /etc/crontab file using the pico editor:0[tab]0[tab]*[tab]*[tab]*[tab]root[tab]cd /Applications/ ; open ./dockiCal.app[robg adds: replace [tab] with a press of the tab key]
This sets a cron job to run the script at midnight every night which, in turn, updates the date on the iCal icon in the dock. You'll need to keep your hard drive awake at midnight, as cron jobs won't activate on a sleeping drive.
[robg adds: You'll need to use sudo to edit the crontab file in /etc; another option is to create a crontab for your user, as explained in this hint.]

