Since running the export command in the shell will only set the environment variable temporarily, you > should follow the process on your OS to make it permanent. On a Mac, add the following line to the > ~/.bash_profile:
export DOCKER_HOST=tcp://$(boot2docker ip 2>/dev/null):2375
wouldn't this only work via .bash_profile if the shells were launched after boot2docker init and boot2docker up were run?
edit: referring to this bit: export DOCKER_HOST=tcp://$(boot2docker ip 2>/dev/null):2375 in this section