Arquillian is a testing framework which lets you write real integration tests, run inside the container of your choice. With Arquillian you will be writing micro-deployments for your tests, small Java artifacts that is, which contains the bare minimum of classes and resoruces needed for your test to be executed within your container. To build these artifacts you will be using the ShrinkWrap API.
Lately I have been looking into asynchronous method invocations in Java EE 6. My use case was to execute multiple search engine queries in parallel and then collect the results afterwards, instead of having to wait for each query to finish before executing the next one etc. In Java EE 6 (EJB 3.1) you can implement asynchronous methods on your session beans, which means that the EJB container returns control to the client before executing the actual method.