"When an individual receives an email in Gmail with flight, hotel, restaurant, or ticketed event information, that event will be automatically added to their Google Calendar, complete with things like flight numbers and check-in times.
Calendar will even update those events if plans change and a new email is received (for instance, when a flight is delayed or a reservation pushed back).
This feature will be enabled by default on desktop and mobile (both iOS and Android) for all Google Apps customers―with the exception of Google Apps for Government domains, for whom the feature is not available.
Events from Gmail added to Calendar will be visible only to calendar owners by default (those with delegated access will not see these events).
Calendar owners will be able to delete any individual unwanted events as well as adjust visibility settings, or disable the feature altogether, in their Calendar settings if so desired."