The latest version of MythTV is now reached 0.28. This new MythTV 0.28 has a special PPA repository so we can easily install this MythTV 0.28 on Ubuntu 14.04 Trusty Tahr. I am not sure if in the future MythTV still uses this PPA for any new MythTV version. But at least, this PPA works for version 0.28.
How to install this MythTV PPA repository:
sudo add-apt-repository ppa:mythbuntu/0.28
The following link describes any new features and updates to MythTV 0.28