I just found this: http://support.google.com/calendar/bin/answer.py?hl=en&answer=99358
The Apple iCal directions suggest this url (and it says that newer versions of iCal support CalDAV): https://www.google.com/calendar/dav/YOUREMAIL@DOMAIN.COM/user
Note at the end it changes '/events' to '/user'. Might be worth a try?
[1] GnuTLS recv error (-9): A TLS packet with unexpected length was received
Different - at least I'm past the login now :P
I should mention, this is Ubuntu 10.10. Might be a tad outdated.