
I came across this problem while setting up Docker on my OSX environment , and after searching the web , I found a method that works well, and cures the problem.
Basically once the Virtualbox VM is created you need to edit the network adapter drivers and set them to "PCNET-FAST III" instead of the paravirtualised drivers. You need to do both adapters, and then restart boot2docker.
You will notice that you get the correct settings now in your /etc/resolv.conf file.
This was annoying me, and meant I had to reset the settings in the above file everytime I start docker - which is not ideal.
Hope this saves you some time.