I've heard good things about Apigee. My understanding is that their backend-as-a-service is built upon the acquired and open-sourced usergrid technology, which

I've heard good things about Apigee. My understanding is that their backend-as-a-service is built upon the acquired and open-sourced usergrid technology, which leaves you the option of hosting it yourself in the event they ever go ahead and terminate their own service. That's not a bad out to have.