First off thank you for all the interest in EngineYard! We are very excited about ramping up the service. So watch us closely over the next few weeks to learn more.
A lot of people have been asking about more details on our setup. I wrote a lengthy blog post that goes into some details about what we have put together. You can read it here:
http://brainspl.at/articles/2006/09/24/engineyard-technology-stack
