@mnisbet:
I don't think that Google Calendar supports subscribing to iCal feeds that require authentication (i.e. like the DueSoon.ics file that OF for iPhone creates on MobileMe).
The way I have got around the limitation is as follows:
1) Log in to
http://me.com/
2) Locate the DueSoon.ics file in your iDisk and select it.
3) Click on the 'Share File...' button in the last pane of the iDisk "Finder"
4) Untick the 'Link expires after...' checkbox
5) Click on the 'Share' confirmation button
6) Now, copy the link that the file has been shared at (it will be displayed in that last pane again and will be something like:
http://files.me.com/YOURUSERNAME/randomstringhere)
7) You can then use this link to add it into Google Calendar as a subscription in the normal way
I suppose the main thing to be aware of with this way of doing things is that someone could guess the link to your calendar as the random string isn't that long.
Hope that works for you too
Paul.