1. A method of sharing information comprising: at a server system: enabling participation by a plurality of clients in a first multi-dimensional virtual environment and a second multi-dimensional virtual environment: transmitting to a first client associated with a first user participating in the first multi-dimensional virtual environment data corresponding to a plurality of objects in the first multi-dimensional virtual environment, the plurality of objects including a first object that is not a portal to any other multi-dimensional virtual environment and a second object; receiving from the first user of the first client an annotation that is associated with the second object; identifying a degree of separation between a second client associated with a second user and the first user in a social network; determining whether the second user can access the first multi-dimensional virtual environment based on the degree of separation between the second user and the first user in the social network; responsive to the second user being able to access the first multi-dimensional virtual environment, transmitting to the second client participating in the first multi-dimensional virtual environmental data corresponding to the plurality of objects in the first multi-dimensional virtual environment, the plurality of objects including the first object, the second object and the annotation associated with the second object; receiving from the first client participating in the first multi-dimensional virtual environment data indicating that a portal attribute of the first object in the first multi-dimensional virtual environment has been set, causing the first object to become a portal to the second multi-dimensional virtual environment; receiving from the second client participating in the first multi-dimensional virtual environment data indicating that the second client has invoked the first object; and transmitting to the second client data representing objects in the second multi-dimensional virtual environment.