Modern TV's have addressed this issue by programing tiny phase shifting into their pixle technology to reduce the chance of burn in. This particular TV in question uses TFT technology for the screen which is the same technology in my computer monitor so the chance of burn in is almost none.
You would have to leave the game paused for at least 12 hours, on the same sceen, to do any damage.
I'll try to dig up some links for ya though... Hang on
Current Gear: Sammy DLP Sony DVD [pre-HDMI] Sony STR-DE 995 Sony speakers
Here's a cool YAHOO answer to the question relating to an LCD set: Click Me I can't verify if this is true but you should be OK.
Also this post: CrutchField Advisor
And from Flat TV People