Deis happens to be built around Chef with a workflow deeply inspired by Heroku. We believe strongly in that approach. Other PaaS's are working with more experimental technologies like CoreOS and etcd, others are going the Erlang route, others seem to be writing things from scratch in Go -- with all of it Docker compatible.
We think this is fantastic for the industry and for consumers (software teams) who will soon have lots of choices in open PaaS.