I recently got my hands on an Asus Nexus 7 tablet. In it self, maybe not a groundbreaking device, if it wasn't for the fact that Canonical will use it as their reference device for running Ubuntu on tablets and dual (or more) core mobile phones. Just to be clear, this is no dual boot, emulator, nor "chroot"-trick. The OS boots natively, and brings up the standard Ubuntu Unity desktop. The kernel is copied from (or based on) Google's Android 4.1 kernel for the Nexus 7, which includes several non-committed changes, as well as binary drivers and firmware. See here fore more information.
A decent proof-of-concept build of Ubuntu 13.04 is already available, and it runs fine on the Nexus 7. If you're running Ubuntu on your desktop, a pre-packaged installer is available from the a repository. Alternatively, download the boot and userdata images, and install using fastboot yourself. (All commands below need sudo).
fastboot erase boot
fastboot erase userdata
fastboot flash boot raring-preinstalled-desktop-armhf+nexus7.bootimg
fastboot flash userdata raring-preinstalled-desktop-armhf+nexus7.img
Now, I said proof-of-concept, and what you get with this image is not really that handy on a tablet. So far, it just starts up a desktop Window Manager, which is not too comfortable with a touch screen. However, with a USB On-the-Go (OTG) adapter, you can plug in a USB hub, keyboard and mouse. Now it becomes usable like any other desktop. I got one of these compact ones from Deal Extreme, However, due to the rounded shape of the Asus Nexus 7, I had to chisel off a few millimetres to make it fit. The version with a wire would probably had worked better. Maybe also interesting to try would be a HDMI adapter (I'm not sure if that particular one works). Finally, the missing bit to have a fully functional docking setup would be charging while the OTG cable is connected. The Ubuntu FAQ mentions that this will be enabled, but you'll probably need yet another special adapter cable to piece it all together.
What's impressive about the current offering is that most, if not all, packages have already been compiled for the ARM architecture and are available in the Ubuntu repositories. This is very welcome, as it frees the tablet from the Android markets, and brings in an enormous selection of free and open source software. Not all of it is immediately suited for a small touch screen on a slow CPU, but that will change over time.
On a whim, I tried apt-get install emacs and eclipse. Both downloaded and worked fine, however, even with a four core CPU, ARM is not up to Eclipse quite yet. It should also be noted that the desktop UI has some unnecessary features which notably slows down the experience. For example, eye-candy like fading transitions when ALT-TABing between windows is enabled.
In conclusion, this is a very interesting first move from Canonical, and more GNU/Linux distributions will surely follow. With more alternatives and variety in this space, it will hopefully open people's eyes up to the fact that the mobile phones and tablets they carry around are full-fledged computers in themselves, with no reason to remain restricted to a single OS from a single vendor. Maybe it will eventually turn stupid laws which makes it illegal to hack and experiment on these devices.