USEFUL LINKS ON PLASMA DISPLAYS
Panasonic presents advice from the video purist perspective. A very detailed article about the plasma displays.
Pioneer Electronics published a white paper on actual testing performed with three plasma TVs.
"...while image retention can occur in modern plasmas, the effect is temporary. After the 48-hour torture test, all three of the plasma TVs that were tested showed clearly visible images from the game menu <...> However, after regular video material (a DVD movie set to continuously loop) was played through the sets for 24 hours, the image completely disappeared from all three plasmas, leaving no trace."
AVSForum has a thread commenting on plasma TV burn-in.
Find your plasma model on one of the AVS Forums.
Another forum on Ecoustics.com with lots of useful information on plasma TVs.
One more article on plasma burn-in issue from PlasmaTVBuyingGuide.com by Jack Burden.