Ardour has been updated to v2.6.1 a bit sooner than expected. This update fixes one very notable and ugly bug that was still affecting 2.6 (plugin automation tracks would be drawn in the wrong place on the screen).
For those waiting on Mac OS X releases a 2.6 native release is already available and PPC will follow early next week; both will be updated to 2.6.1.
It's not clear if or when there will be an X11-based release.