OMG, YOU JUST MADE MY DAY.
I was puloing my hair out due to this posterization issue. I purchased Panny plasma (P55VT50) this April. It is a fantastic display, dont get me wrong. I'm now saved from the VT20 floating blacks. But I noticed this strange color banding, oily face issue and as much as I fiddled with various settings I was not bale to get rid of it at all.
Adding just a little bit of noise gets rid of it.
It is a compromise for sure, I added just a little uniform noise with ffdshow not to otherwise ruin a contrasty and vivid picture; so the most offending scenes still display it - if I look for it, but otherwise its gone. SO SIMPLE.