In order to get the updates for Ubuntu to take MythTV to 0.20.2 you need to add the following to your /etc/apt/sources.list file:

deb http://us.archive.ubuntu.com/ubuntu/ edgy-proposed main restricted universe multiverse

deb-src http://us.archive.ubuntu.com/ubuntu/ edgy-proposed main restricted universe multiverse

After doing this run the following commands:

sudo apt-get update

sudo apt-get upgrade

In addition to the MythTV updates a few other things should be available. I went ahead and just got everything and have suffered no ill effects.

After updating, make sure to shutdown the backend before running mythtv-setup to change the data provider.

sudo /etc/init.d/mythtv-backend stop

After running mythtv-setup, make sure that you start the backend back up, then run mythfilldatabase.