BusyCal 1.5
The new MobileMe Calendar acts as a CalDAV server for sharing calendars with CalDAV clients like iCal and the iOS Calendar app. Great, but many of us who have needed real calendar sharing before the new MobileMe Calendar have long been using BusyMac’s BusyCal. With the release of version 1.5, BusyCal can now sync with the new MobileMe Calendar as well, if you wish, although there’s no need to switch to the new MobileMe Calendar if everything is working well now. If you do wish to switch to the new MobileMe Calendar with BusyCal, be sure to read BusyMac’s “Overview of the new MobileMe Calendar” and “Upgrading to the new MobileMe Calendar” support articles first, since the process is non-trivial.
Put bluntly, I’m not switching to the new MobileMe Calendar at the moment, since the only notable advantages in our workflow would be sharing of events between our MacBooks while we were on the road and an alternative to Google Calendar for sharing of calendars across the Internet. Otherwise, BusyCal’s LAN-based event sharing meets all our needs, and I simply don’t wish to spend the time and effort associated with switching to the new MobileMe Calendar for the minimal gain in capabilities.
Users of BusyMac’s earlier calendar sharing solution, BusySync (which enables calendar sharing for calendars that you work with in iCal), should note that BusySync can only read calendars hosted on the new MobileMe Calendar; they can’t be written to or shared elsewhere. If you really need BusySync’s capabilities in addition to read-write support for the new MobileMe Calendar, the only option at the moment is to upgrade to BusyCal, which is in essence a melding of BusySync and iCal, with notable improvements to iCal’s interface. ($49 single user/$79 family pack new, $20 upgrade from BusySync, free update, 6.6 MB)
BusyCal also has built-in WAN sharing, too, so there's no reason to even use MobileMe if you've got a BusyCal server sitting behind an opened port on a router somewhere.
Indeed - the only hard part there is the open port that's accessible from the outside Internet for most people. Before we moved to a virtual server, that was how we were sharing things as well.