Since Geronimo exchanges config information via serialized form of Java objects, its imperative that the serializable classes declare a serialVersionUID. If they don't then the serialized form is not necessarily compatible across Java implementations (or even Java compilers) .
The case in point is the wire format classes in ActiveMQ (e.g. "org.codehaus.activemq.message.DefaultWireFormat") which are marked serializable and do not declare a static ID. I've tried raising this with ActiveMQ  but without success.
I can provide the required SUID in each case, but it looks like I might need help to get it into the ActiveMQ code.