(disclosure, I'm working on Cloud Foundry as dev advocate)
To address your question specifically about Google App Engine, GAE is closed source, so you can't just deploy that on your own private environment. As cloudssky points out, there's something called AppScale which is similar to an implementation of GAE which may work for you.
For Cloud Foundry, actually it can be run on Grizzly or Havana and devstack - check out https://groups.google.com/a/cloudfoundry.org/d/topic/bosh-users/opV8dRdVhcQ/ (this mailing list discussion) for example. There are a bunch of folks on Twitter like @ferdy, @drnic, @anynines who should be able to help you and there are many organisations running CF on top of OpenStack without issues (actually AnyNines recently blogged about having moved their live PaaS from vSphere to OpenStack http://blog.cloudfoundry.com/2014/01/29/migrating-a-cloud-foundry-paas-to-run-on-openstack/ (Migrating a Cloud Foundry to run on OpenStack)
In addition, Piston and Canonical have both stated their intentions to support CF on top of OpenStack.
I cannot speak for other PaaS options as I am not experience with them.
Red Hat's OpenShift Platform as a Service will run on RHEL 6, CentOs 6.5 or Fedora 19. It you are looking for installation support, go to http://install.openshift.com or try using the Heat templates in https://github.com/openstack/heat-templates (https://github.com/openstack/heat-tem...) These should get you started.