COM+ Event System
Windows Vista Service Details
I actually cannot name any real applications that make use of this service, but it is an event model that passes information between processes.
Supports System Event Notification Service (SENS), which provides automatic distribution of events to subscribing Component Object Model (COM) components. If the service is stopped, SENS will close and will not be able to provide logon and logoff notifications. If this service is disabled, any services that explicitly depend on it will fail to start.
Consequences of Stopping:
Background Intelligent Transfer Service depends on this which is required by Windows Update.
All services listed in 'Required For' will be unable to function
Background Intelligent Transfer Service, COM+ System Application, DFS Replication, System Event Notification Service