
Fast on the heels of MythDora, Mythbuntu, a project that aims at "(P)roviding an Ubuntu based MythTV distribution that is easy to configure, maintain, and use", just released its version 7.04 Public Alpha 1. You may download the image via BitTorrent or direct download.
Just like any other software in its alpha stage, expect a lot of bugs to pop up during testing.
Good luck!