Following in the footsteps of the original Nook Color, the Barnes & Noble Nook Tablet is already proving to be a popular development platform. First it got root and the full Android Market, and now hardworking developers have gotten Ubuntu to run the device.
While the full Linux OS is in fact running completely on the tablet's hardware, it is not doing so directly or on its own. Instead, it is running within the Nook's proprietary Android OS, as a process in the background. In order to actually use Ubuntu, you have to start the OS and a VNC server from the tablet's terminal, and then open a VNC viewer application on the Nook to use it. So although things like Firefox, application installation, and a full Xorg GUI work, Ubuntu is of little or no practical use thanks to lag.
However, the developers hope that they can use Ubuntu to break the Nook's locked bootloader, thus allowing users to install custom OSs like Cyanogenmod on the device. If their efforts go as planned, soon the Nook Tablet could be running Ice Cream Sandwich just like the Kindle Fire.[XDA-Developers]