I was recently sent a link to a very interesting paper on the weakness of the Oracle Password hashing by TechRepublic. It talks about how easy it is to crack the oracle passwords and what can be done to strengthen your passwords. Any DBA's out there might find it interesting. The link to the PDF white paper follows. Oracle has known about this problem for a long time and needs to have pressure placed on them to upgrade security.
This version of the white paper does NOT contain any of the code to actually hack the password, but does discuss the weaknesses.