Canonical's brand-spanking new combination of Android and the Ubuntu Linux distribution is easily the most exciting software development for Android since Ice Cream Sandwich. Basically it packs an ARM-based version of Ubuntu into a standard Android phone, activating it only when docked to a computer via HDMI. The software and basic capabilities were announced earlier today, but a Canonical employee was nice enough to post a live demonstration of Ubuntu on Android to YouTube.
As promised, as soon as the phone (a Motorola Atrix 2) is placed in the dock, the full Ubuntu OS opens on the computer monitor. (A mouse and keyboard are probably connected via Bluetooth.) The phone is still running Android in the background, and Ubuntu has access to not only the files and folders on the phone, but the video out and apps as well, not unlike WebTop. Ubuntu uses the phone as storage and a network connection, and Android alerts show up on the desktop as well, keeping a user connected at all times.
There are some important limitations: first, Canonical isn't releasing Ubuntu for Android to the public. They're hoping to license the software to manufacturers as an add-in on new phones, so no existing phones will be officially supported. Next, phones must have at least a dual-core process or and 512MB of RAM (understandable with all the power requirements) and HDMI-out to qualify. Lastly, Ubuntu is running on ARM hardware, so programs designed for x86 (i.e. most of the desktop applications out there) won't work immediately. Expect to see more out of Canonical in the next few months, and perhaps the first Ubuntu on Android phones before 2013.