I have a 42" G10 that I use for gaming. Input lag is imperceptible. I've seen where other forum members have posted input lag tests on the '09 Pannys and they consistently show somewhere between 20 and 30 ms of input lag- which is very good. You'll be hard pressed to do better with just about any flat panel and, as I said, I can't detect any lag at all when playing, and I primarily play competitive FPS's like Halo, COD, and Killzone 2.
If you own/watch a lot of Blu-Ray movies, you might look to the V10 series, as it incorporates a proper 24p mode that refreshes at 96hz, whereas the lines under the V10 only go up to 48hz, which introduces headache-inducing flicker. Not everyone cares about judder and proper 24p handling, though- and if you want to save money or go with a bigger display size, etc.- the G10 and the two S series' both look great whilst displaying BR movies at 60hz.