My Nexus 4 is ready for Ubuntu Touch 14.10. Actually it's on the Internet already and one can download right away. However I want to wait until RTM-version (Release To Manufacturing) is available. Other operating systems Nexus 4 can run are Android, Cyanogen Mod, Firefox OS and Sailfish OS (not officially available yet).
Meanwhile there is some homework to be done. Ubuntu Touch has a development environment ready for download. Naturally Ubuntu (14.04) is needed. Take a look at instructions on how to install dev environment on your Ubuntu: http://2buntu.com/articles/1509/ubuntu-touch-app-development-getting-started/
My Nexus 7 (2012) with
Ubuntu Touch last autumn 2013