Have you used any Oracle specific features?
No, We have not used any oracle specific issues. But we have used some value objects which are used in both web tier and middle tier. Oracle 9iAS doesn't create any war and ear files. so, we do not know where to place these value objects.
I have nearly the same problem but in the other direction, a customer wants me to use OracleAS10g but I am only experienced in JBoss.
Maybe we can help each other to get both tasks done?