With this improvement many MSP's or multi-site admins would be able to set a holiday schedule once a year with specific voicemail messages linked to each holiday in their schedule.
Currently we are having to set calendar reminders before every relevant holiday to remember to update the dial plan of each site (client in our case), in order to match the holiday voicemail message to the already scheduled upcoming holiday. This of course can be mitigated by using generic holiday messages, but not all clients are so flexible.