1. A method comprising: establishing an instant messaging session between a first client device and a second client device; sending a request from the first client device to a calendar server for a key to access calendar data of a user of the first client device; receiving the key at the first client device from the calendar server; transmitting the key via the instant messaging session from the first client device to the second client device; transmitting an additional request from the first client device to the calendar server for display preferences associated with the user of the first client device, the display preferences specifying a manner of displaying the calendar data of the user of the first client device to a user of the second client device; receiving the display preferences at the first client device from the calendar server; and transmitting the display preferences from the first client device to the second client device via the instant messaging session.