I’d like to take a look at JMS and the leading contenders for an open source JMS provider seem to be:

• Apache ActiveMQ
• OpenJMS
• JBoss Messaging
• JORAM

Circumstances are pushing me to JORAM by a process of elimination:

• ActiveMQ seems to be happiest with Java 1.5
• The last release of OpenJMS seems to have been back in June 2006
• JBoss Messaging appears to only run inside of JBoss

I’ll let you know how things work out.