This is actually a tip from the dusty old box, although I imagine that there are still people around with SoaSuite/Jdeveloper 10g. I got a VMware image with SoaSuite10133. And I couldn't connect to it with JDeveloper from outside the VM. And I should have the solution somewhere but I couldn't reproduce it. The solution lies in the opmn.xml found in $ORACLE_HOME/opmn/conf.

There you'll find a notification-server element. It propbably does not have the ipaddr node below it by default. But add it like below with 0.0.0.0 as ip-addresses. Doing so enables you to connect with a jdeveloper on a remote machine.

I wrote about connecting to an Oracle Application Server/SoaSuite within a VM in greater detail here, but I did not include the actual opmn.xml snippet like above.