1. A method of facilitating transitioning use of an application by a user from a first client device or system to a second device or system, comprising: at the first client device or system under control of a respective user: executing a first application; performing a handoff operation, comprising: when the first client device or system is positioned within a predefined proximity of the second client device or system, transmitting application information, associated with the first application, to the second device or system; wherein the first application has a first client device user interface state when the handoff operation is performed; at the first client device or system, in response to receiving from another client device or system application information associated with a second application executed by the other first client device or system: executing a third application corresponding to the second application with an initial user interface state corresponding to a user interface state of the other client device or system.