the dc/os update is only available to new customers though. Deployments are always stuck with the version they were deployed with. IMHO ACS is nothing more than a template, not an actual service that you deploy your containers to (like Google's Container Engine)

It is true that there is no update path at this time. Our focus is on ensuring the software runs best on Azure. Upgrading a container service is a complex affair with different users wanting different experiences. With the open sourcing of ACS Engine (also part of this same announcement) we are providing a channel through which users can work with our team to define optimal upgrade strategies that will eventually be rolled into the service itself.

Microsoft open sources its Azure Container Service Engine and launches deeper Kubernetes integration