A user on the AVSForum has a post detailing the recommended settings of a fellow forum user, and settings from Sony to decrease the mura effect.
"I played the HD-DVD Batman Begins (you know, the other DC Comic Hero besides Superman!) and paused the film in two spots. One spot is a dark scene in the movie (indoors, minimal lighting) and the other scene contains lots of light (outdoors and snow). I have paused the film in two locations and used the following settings:
Vivid (default factory settings)
Standard (default factory settings - BTW - this is the setting I use w/ some tweakage, but for the purpose of this photo shoot, I put Standard settings back to default)
Custom (this is where I dialed in your settings. I used minimal backlight, picture set to 90, light sensor ON and power saver HIGH)
Granted, the photography isn't the best in the world, but the camera setting was the same for all three test groups and the pictures speak for themselves.
Here they are in the following order: Vivid, Standard, Andrew's Settings (Custom)"