> How does Docker mesh with something like continuous deployment?
Very well. Because any source repository with a Dockerfile can be built into a container with no other out-of-band information, it is very easy to compose your ideal delivery pipeline with docker as the "lego" brick.
Docker+Jenkins and Docker+buildbot are popular combinations.
> How many layers until the AUFS falls down?
The hardcoded limit is 42 layers. But future versions of docker will store a container's history separately from the aufs layers, so you can have an arbitrary number of build steps.