This question was posited by puppet labs. Without knowing the background or motive of the person asking the question given the source; Anyone having spent the shortest amount of time testing Docker would know the answer. The real question puppet labs should have asked is whether or not there was an opportunity for tools like puppet, chef, salt etc. and the container?
While docker's dockerfile does provide some configuration management syntax it is not a complete mechanism as it is missing the orchestration component. One only needs to look at open stack in order to find much of the linkage that is otherwise missing.
Puppet and chef and the other like tools have much more to fear than simple containers. These configuration management tools are attempting to homogenize the many operating systems that are out there today. This is a difficult task given the many differences in the systems.