Ok, I am answering my own post, after trying out and finding the best approach to go about.

(1) Do *NOT* use oracle.jdbc.driver.OracleDriver for Driver Class. Please *USE* this instead as clearly documented by Oracle Corporation -

oracle.jdbc.OracleDriver

as clearly documented by Oracle Corp. This is especially true in Oracle11g environment.

(2) Use this in Hibernate CFG file until such time Hibernate has explicit dialect for Oracle11g and JBoss uses that Hibernate version -

<property name="dialect">org.hibernate.dialect.Oracle10gDialect</property