I am very interested in using the @Asynchronous and Event.raiseAsynchronousEvent functionality. However, its lack of access to the Conversation and Session scope is difficult to work around. The documentation states the following:
We usually use an asynchronous call when we want to return an immediate response to the client, and let some expensive work be processed in the background. This pattern works very well in applications which use AJAX, where the client can automatically poll the server for the result of the work.