After reading the EJB3.0 specification it has become clear to me that Annotations are a perfect abstraction for our configuration meta model. Therefore all new container configurations will be defined in Annotations.
There are a lot of advantages with this approach:
1) It is very easy to express anything and parse anything in XML format as we have an easy mapping from XML to the meta model
2) We are not limited to XML as the configuration format. ANother idea I have is to define container configurations as Java classes with annotations sprinkled in.
3) EJB3 is all about removing deployment descriptors. A configuration model expressed as annotations can be embedded in Bean class files like regular EJB annotations are.