So far, we've reviewed creating simple artifacts. Most deployments have either been a WAR file or a JAR file. Arquillian does support RAR and EAR deployment; it's just that in Java EE 6 the need for having EARs has been greatly reduced–you can now deploy your EJBs into your WAR module, so it's unnecessary to have an external EJB-JAR.
There are some modular approaches to the application development and deployment that may require you to build out many deployable archives. OSGi is one standard that helps with it, but other tools exist such as JBoss modules that support similar packaging structures.
Your application may choose to deploy as an EAR file. This would be based on the library usage as well as the decided deployment structure. In Java EE 6, you get all of the capabilities of an EAR deployment with EJB JARs packaged in the WAR, as well as being able to package EJBs directly in your WAR file.
The enterprise archives with Arquillian can be a little tricky...