Possible to drop down to Ubuntu in Google Chrome OS?

I've heard that Google Chrome OS is built开发者_运维问答 upon Ubuntu.

Does this mean it's possible to drop down to Ubuntu shell and install native applications?

---

I just got a Cr-48 notebook today. You can enter the developer mode and get access to the shell. Unfortunately, no package manager is installed, so although it's technically a Linux, you can only run the existing programs. You either rebuild the ChromiumOS image yourself to add any program, or install Ubuntu on a spare partition.

---

It is possible to install packages from Arch Linux, amazingly enough. As the previous answerer mentioned, there is no package manager on the Cr-48, so you are limited in which Linux distributions you get packages from. Those have to be really simple and tar-based.