Hello,
Matthias Broecheler and I are at GraphLab 2012 presenting a poster about Titan.
This poster presents an overview of Titan along with some excellent stress testing done by Matthias and Dan LaRoque. The stress test uses a 6 machine Titan cluster with 14 read/write servers slamming Titan with various read/writes. The results are presented in terms of the number of bytes being read/write from disk, the average runtime of the queries, the cost of a transaction on Amazon EC2, and a speculation of the number of concurrent users are concurrently interacting.
Enjoy!,
Marko.