It makes me think that there's something wrong with the Ruby VM when someone has to offer a service like this. The Ruby community should expect great performance out-of-the-box, and the VM should tune itself, automatically.
VMs can tune themselves up to a point but there is always need to give them some precise bounds/goals, methinks.
>java -XX:+AggressiveOpts -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+PrintFlagsFinal -version
It will list about 700 options.
That being said, I'd like to try this service, the guys behind it seem to really know what they are doing.