Actually, Oracle does have a product that allows for integration. It works
with Project 2003 client out-of-the-box. However, if you want to integrate
with Project Server, you need to customize their code and the Project Server
environment. The interface I tested is available from Oracle for version
11.5.8.
The tool is available from Microsoft and is called "Oracle Project Connect".
Very little is available on their website, so you will want to contact
Oracle directly.