The major impetus for this release is the shutdown of TMS Labs; among other changes this adds Schedules Direct support. The 0.20.2 release notes have a list of the two major and many minor changes since 0.20.1.

Major Changes

* Support for SchedulesDirect including caching and multiple MythTV video sources per SD lineup
* Reduced mythfrontend memory consumption by up to 75% depending on theme and resolution.

Features

* Faster startup of mythfrontend and mythtv-setup from changes to theme prescaling.
* Improved default theme images with better scaling and anti-aliasing
* Backported XMLTV changes to help former Zap2It users switch to a new grabber
* Improved --version output, including the branch name.
* Entire UPnP stack from trunk backported to address numerous UPnP problems

http://www.mythtv.org/