For anyone who wants to try out the new Ubuntu Touch dual-boot, here's how (if your device isn't supported yet):
1. Download and install the attached apk.
2. Edit your build.prop (I recommend using an build.prop editor from the Play Store, but you can also do it manually)
Change the three original lines to look like this:
3. Reboot into Ubuntu Touch!
Notes: A regular boot will boot your device into android, and you will have to reboot into Ubuntu Touch from within the installer app.
You will not be able to boot into recovery without uninstalling Ubuntu Touch.
Your backups may or may not be deleted when uninstalling Ubuntu Touch.
Warning: I own an Optimus G, very similar to the Nexus 4. As devices vary, so will compatibility. There are no promises that it will work well for all devices and I take no responsibility if something goes wrong, though I'm willing to help out if it does.
Edit: Feel free to try on your device, but will work best/only on Nexus 4/Optimus G variants