Arquillian support for OSGi is still in its infant stages. As support for the standard grows within JBoss, I believe its usage will become more stable and more robust. We can go ahead and develop and deploy usable OSGi bundles, but until there is strong integration to the Java EE platform it may not be an overly useful tool for your arsenal.
When it comes to most other application servers, we can actually use their default container adapters to do work. This logically makes more sense; however, we lose some features such as bundle or bundle-context injection. We could manually lookup the service if we had access to a managed object to provide the bundle or bundle context.
One of the benefits of using GlassFish for your OSGi runtime in your application server is that your application likely has little to change to work with it. Obviously, you lose some injection capabilities for bundle resources, but that may not be a needed capability for your testing. The main use case right now for...