There's a great explanation here: http://blog.docker.io/2013/10/docker-0-6-5-links-container-n...
With the new Links functionality, this is much easier, but are you planning to ever have the ability to use a single Dockerfile to deploy an application which may contain multiple images (with links between them)? I want to be able to do "docker build ." and have my application up and running when it finishes.
Yes, definitely :)