Some sites are getting that helping the user with date related information by providing the information in a standard format that allows the user to drop the information into their calendar tool. One such site is Upcoming.org's iCal Integration.
The I recently ran across a similar tool, but for vCal, on the Hilton site. When you book a room on the Hilton site the site provides a standard calendar format data chunk that drops right into Outlook or other vCal ready application. This is a no fuss and no error means of helping the user get the information right and dropping it right into their Personal InfoCloud so they can synch that with their mobile phone or PDA and have the correct information (with the confirmation number) within ready reach at all times.