There hasn't yet been a "first generation cloud computing automation framework", so it's kind of impossible to be building the "next generation". That first generation is pretty much what everybody in the field is working on (including my company).

But Vertebra sounds like an interesting approach for the applications where it fits. And repurposing an existing protocol for RPC is always interesting, they've chosen the surprising, and novel, XMPP (we use a light-weight RPC mechanism that runs over HTTPS that was already part of Webmin, with a fallback to SSH on instances that don't have Webmin or Virtualmin). And they're addressing a niche that no one else is addressing, which is Ruby on Rails in a cloud environment...it could be done with Amazon using SQS to detect rising "pressure" and ramping up new instances as the pressure rises and shutting them down as the pressure decreases. But, Vertebra being focused on RoR probably means that if you're building a RoR app, you'll need to spend a couple of days less time developing that aspect of your deployment. You still have to solve the database scaling issue, and the data sharing and state problems, just like any other large scale deployment...but one less thing to worry about is one less thing to worry about. (And nobody is going to solve all of those other problems automatically.)