Details of a 10g PL/SQL Unwrapper available
Anton has done some research into finding the substitution table but not via reversing the binary but via a simpler method of comparing the clear text (from known PL/SQL) to the compressed text. This is then used to create a complete table that allows unwrapping of PL/SQL for 10g. He has also included some Java code to allow unwrapping of PLB files. This is some nice research. His post is called "Unwrapping 10G wrapped PL/SQL". Also of note is a paper mentioned in his post by three Israeli's "Automatic detection of vulnerabilities in wrapped packages in Oracle"