For Domains whose admins have enabled the ‘enable pre-release features’ checkbox in the Control Panel:
Event timezones – You can now specify the time zone for a given event. You can also set up events which start in one time zone and end in another.
For Domains with ‘enable pre-release features’ checkbox disabled:
Optional attendees: When adding invitees to an event, you now have the ability to communicate the importance of a meeting for each attendee.
Event timezones: Click the “Time zone” link to the right of the date and time fields on the event page to enter the timezone. Events will appear on your calendar according to the current time zone you’re in, and when you change to your destination time zone they’ll be in the right place.