Some more information on the iCal, MobileMe, and Mac OS X 10.6 (Snow Leopard) problem.
Picked up this information on a 10.6 discussion at Apple. Followed the message and I can confirm that it is all day events that cause the problem. I published a calendar with one event, worked fine. Added an all-day event (no start and no stop time), wouldn’t work. Removed the all-day event, problem solved….