MythTV 0.26 Alpha was released this morning as the first development milestone for this open-source PVR/DVR project on its new expedited release schedule.
MythTV 0.25 was released in April
with many changes, but if all goes according to plan, it will be succeeded by MythTV 0.26 next month.
The 0.26 release plans were shared with today's alpha release and it includes a beta release by month's end, an "rc0" release in mid-August, and a final release or an additional alpha release in mid-August.
These details are shared in the MythTV 0.26 Alpha release announcement at MythTV.org
Unfortunately there doesn't appear to be an official change-log yet for the 0.26 series, but last I heard, with this release they were planning to drop X-Video support
and make other video renderer changes.