OpenESB did create a Service Engine to integrate it with Camel
http://wiki.open-esb.java.net/Wiki.jsp?page=CamelSE
However the SE seems a bit outdated as at the time it was targeted for Camel 1.5.
Today Camel 2.5 will hit the streets.
It would probably be a good idea to try to get that SE updated.
However Camel is just
Java code and a set of JAR files. So if you can invoke Java code from OpenESB.
Then
you should also be able to integrate it with Camel without that Service Engine.
I would suggest to get in touch with the OpenESB community and ask them to upgrade the Camel component to leverage Camel 2.5.
And if they need any help they can always get in touch with us at Apache Camel.
http://camel.apache.org/discussion-forums.html