If you do not see calendars being published by other BusyCal or BusySync users on your LAN, it may be because they have their system firewall turned on and it is blocking incoming connections. They should either turn off their system firewall, or allow BusyCal and BusySync traffic to pass through the firewall. The instructions differ depending on which version of Mac OS X you are running:
Note: It is only necessary to modify your firewall settings on computers that are Publishing calendars. It is not necessary to adjust the firewall settings on computers that are only Subscribing to calendars.