I'm not entirely sure WHEN this started... it could have been when I upgraded to 6.0.1, or it could have been when I moved to Snow Leopard, or it could have just randomly stopped working at some point based on some other variable. But now, whenever I try to sync my calendar in iCal, I get:

Now, I've tried going to that URL, providing my credentials, and I get what appears to be valid data.

Anyone have any ideas on what I might be doing wrong? (I've since upgraded to 6.0.2, just in case that was the problem)