I made the mistake last year of buying a 42" LG (42LD490), primarily for use with my Xbox, but was not aware of the potential issue of 'input lag', and my research at the time didn't highlight it. Most reviews don't mention it and, it turns out, most people selling TVs for a living I've spoken to are unaware of it.
The effect of this lag on my gaming (mainly F1...each to their own!) was horrible, always "behind" the action.
I recently did some more research and based on that purchased the Panasonic Viera TX-P42ST30 you suggest. For games it's input lag time is considerably reduced compared with the LG. Sure, not as fast as a CRT, but small enough to be inperceptible.
Anybody thinking of buying a big telly for gaming really need to think about this. My focus is racing but I believe for first person shooters the issue is even more accute.
I would like to see El Reg's reviews of TVs compare their input lag times with CRT...I can't be the only El Reg reader who uses their TV mainly for gaming.