MOM and SOA on Linux?

dogmeant asks: "I have yet to see MOM (message oriented middleware) offerings on Linux much less open source projects that address the same. And while we're at it, what about tools that address SOA/BPM (Service oriented architecture/business process modeling) type architectures on Linux? Is the Open Source community ready to take on challenges like this?" If anyone else out there has this particular itch, maybe this will be another niche in which Open Source software can catch some Enterprise mindshare.