Hello,
I have this tv and use it for gaming and the lag when using the Beatles Rock Band auto calibration guitars reads 28ms. I recently bought this tv after having the Sony KDL40EX503 which had a lag rating of 68ms when using exactly the same equipment, and every lcd is going to have far more lag than any plasma. My sessions of MW2 have really benefited from the lack of lag although i still seem to be killed far to often of course and i swear i have pairs of socks older than most of the people shooting me lol! I should add i have not had an issue with lag with either the PS3 or 360 since i bought this tv.
The figure you quote does seem excessive and all my rock band games and dj hero are set to 28ms which is absolutely spot on in terms of calibration but perhaps they measure the lag differently, i'm not sure about that though, perhaps others may be able to shed some light? If i remember correctly from the research i done before i bought my tv the 28ms is about right, perhaps the Panasonic website may shed some light?