It's been about for a while and can be used to stress test storage systems.
It's a simple single binary file that generates I/O load on a storage system using Oracle's I/O call stack.
No need to install Oracle at all!
Unfortunately for me, it only works with file systems that have Async I/O enabled.
I did not, and therefore could not use ORION.
When I finally get time to install Oracle on my new Oracle Enterprise Linux 6.1 environment, I'll give it a go.