Welcome to the XBean project
The goal of XBean project is to created a plugin based server analogous to Eclipse being a plugin based IDE. XBean will be able to discover, download and install server plugins from an Internet based repository. In addition, we include support for multiple IoC systems, support for running with no IoC system, JMX without JMX code, lifecycle and class loader management, and a rock solid Spring integration.
Craig has a great post which describes how XBean can really help provide a customized XML language with Spring XML configuration extensibility. We're really happy with it so far and have moved away from XSLT and custom DOM processing to the simpler XBean model in ActiveMQ and Jencks with ServiceMix to follow suit real soon now.