This is actually closer to Google-Style operability than it is to Twitter-Style operability. :) Twitter doesn't have an equivalent of GSLB (software load balancer), which is essentially what this is.
I haven't actually seen anything like GSLB anywhere else. With classic load balancing we've always been taught to proxy traffic through a single point of entry. GSLB flips that on its head and rather provides routing information which clients can then use for the next set of requests. I'm attempting to develop something similar within https://github.com/micro but it's going to be a long time before I even get marginally close to something as powerful as Google has.