The rise in popularity of online calendaring applications such as Google Calendar and Yahoo Calendar has spurred these megalyths to support the emerging CALDAV standard (RFC 4791) for calendar event interoperability between disparate systems. On the client side, Mozilla's Firebird is already supporting CALDAV. This means that fully-compliant CALDAV servers such as Google Calendar can intelligently sync calendar information automatically with your preferred calendaring client software.
Domino already supports WEBDAV, to which CALDAV is the calendaring extension.
It would make perfect logical sense for Domino to support CALDAV fully, out of the box.