ServiceMix 4 is built on an all new OSGi architecture and contains major enhancements to the underlying container. There have been several milestone releases but we need more feedback from the community as we get closer to a release. I encourage anyone currently using or interested in ServiceMix to try out the new ServiceMix 4 Milestone 3 release and give us some feedback, scream at us, praise it, or whatever your initial reaction is. This release is a fairly stable build and should serve as a good test for anyone evaluating ServiceMix and deciding to go with version 3 or 4. Documentation is somewhat lean ;-) but once we get some feedback and things are solid we can add the necessary docs. Come on, you know you want to try it. Go ahead and give it a shot!