Google has posted details <http://www.theinquirer.net/inquirer/news/2390180/google-will-now-allow-android-and-linux-usb-boot-on-chromebooks> of how to boot up your choice of Linux distro (including Android) on a Chromebook, as an alternative to its built-in ChromeOS. This is still extremely fiddly, risk-prone and not for the faint-of-heart.