No, Docker is not becoming red hat - specific. From a technical standpoint this announcement means two things:

1) Docker 0.7 will run on vanilla kernels out of the box. This means virtually all distros will be supported. It also means wider support for hosting providers which don't allow custom kernels (Google Compute Engine for example).

2) Future versions of Docker will optionally support some of the technology used by Red Hat - most prominently libvirt-lxc and selinux.

The more places you can use Docker, the more useful it is :) So we have no intention of locking it into a single distro or paas.

Yes, we will still support Ubuntu, and other non-redhat kernel versions.

This is basically just expanding our current abilities to include areas where we didn't have great support before.

The goal is to have Docker running on all linux platforms, so that everyone can use it regardless of their distro choice.

What do you mean by "what happened with Gluster"? Every project tends to be better packaged for some OSes/distros than others, based on the developers' own expertise. GlusterFS was a bit more rpm-friendly than deb-friendly since long before the acquisition. That hasn't gotten much better, unfortunately, but neither has it gotten significantly worse. There's enough software in the world that barely even runs on any distro other than Ubuntu. Is it really worth complaining every time that's not the case?