I have a problem when publishing calendars from iCal containing "UTC" or "floating" time zone events. I live in the Europe/Berlin timezone and my computer is set to this timezone. Timezone support is also enabled in iCal. When I create 3 events with different timezone setting, one "Europe/Berlin", one "UTC", and the third "Floating", they all are displayed correctly in iCal. However, after publishing them in ical.mac.com (which is also set to the "Europe/Berlin" timezone), only the "Europe/Berlin" event will show up as entered in iCal. The events with the "UTC" or "Floating" timezone setting both display a time-shift of +9 hours. When I subscribe to this calendar all events will be displayed correctly in iCal again, so the problem seems to be with the ical-server. The events were created with iCal, not imported from Outlook or other calendar-applications, so there is no syncing or conversion issue involved.
Same problem with MobileMe calendars - they do not support the floating timezone. I spent a lot of time trying to create floating timezone iCal events with Apple Script and with Objective-C, but it's not possible. Hopefully Apple is going to fix this soon!