I've modded my BookTV listings generator to also produce iCalendar files now too. I don't happen to use iCalendar (.ICS files) myself (yet?), but representing TV listings as iCalendar seems only logical.
So here they are -- you're welcome to subscribe to the feed for your timezone, if you like. Just don't set it to refresh every minute, okay?
And let me know if you have any trouble with it.