I'm suprised to see absolutely zero mention of the Motorola Atrix. A year and a month ago Motorola demoed exactly this concept at CES and shipped it two months later. It's commercial success wasn't as high as expected (understatement), but it shipped. Atrix 2 shipped 7 months later.
What Motorola was pitching back then was the "full" webbrowser experience on a phone. With a custom-built Firefox, you could access all your bookmarks, and maybe a bit more. How is it implemented ? A chroot, with a small linux distro running a never-updatable Firefox and the Android equivalent of Xephyr. No plans whatsoever for other apps.
What Canonical is doing is basically using Atrix hardware, and replacing Motorola's own (very) limited chroot linux distribution with an Ubuntu based one. I'm surprised it took so long. I'm surprised it wasn't Motorola's idea to go see disto vendors like Canonical.