Since I just updated Docker to 1.1.0 I get:
Error response from daemon: client and server don\'t have same version (client : 1.13, server: 1.12)
<
This worked for me: It just shuts the vm down, deletes & recreates it and starts it up again. It re-runs shellinit so your ENV variables get set with the correct IP address when it comes back up.
$ boot2docker poweroff && \
boot2docker delete && \
boot2docker init && \
boot2docker up
$ eval `boot2docker shellinit`