I really hope so, with the work that Red Hat and dotCloud are doing it will be possible for a Docker container to run on any Linux OS - which is a significant first step towards ubiquity.
Whether Heroku's Buildpacks are then able to be layered on top of a Docker container is the question, not impossible as they are open source but will Heroku come on board?
It seems Red Hat's OpenShift is making the moves towards this being possible with their cartridges which are the equivalent of the Heroku Buildpacks.
The key bit is that the community seems to be converging around some standards that could lead to true application portability for PaaS, something we don't really have yet.
Jeff Lindsay wrote https://github.com/progrium/dokku which uses Heroku Buildpacks to build an app and then run it using Docker - it is a very neat little tool : )
Very true, this would be more compelling if Heroku got behind the project themselves because their build packs would be very portable and possibly a future standard.
It seems that Docker is becoming the container of choice but how apps are layered on top is still very much up for debate.
