I provided a link to AVS Forum about cracked plasma tv's and how Samsung is notorious for not honoring their warranty.
A veteran poster on AVS named RandyWalters cut and pasted numerous threads in the link above. Again, this appears to be a major problem. I cut and pasted a few comments from AVS members below from the threads.
"When an internal component fails (like the power supply or a capacitor on a video board etc) it can blow with enough sudden force to crack the plasma panel's glass. I would think that this is the most common cause of the screens spontaneously cracking when someone was just watching TV."
"Lastly, and I have done this, send a registered letter to the Head office in Korea and tell them what scum their local distributor is, and how much bad press they are going to get. The phone will begin to ring."