We have just released the first binary version of Apache Olio for both the PHP and Rails implementation. Both implementations have been tested quite thoroughly now and we think they are robust enough for serious use - especially for performance testing the workloads.
I introduced Olio in a previous post. It is a toolkit that includes a sample web2.0 application implemented in both PHP and Rails that includes a load generator to drive load against the application.
Please visit the Olio site and download the kits. If you find it interesting, I invite you to come join the project.