After reading this thread helped me out so much when picking a TV, I figured I'd address some of the more common concerns and questions after having bought the 60PK540 and having used it for 100+ hours and a couple months. Feel free to ask me any questions about this TV.
About the input lag: it's either minuscule, or non-existent. I was fairly worried about this, as I game quite a bit, running the gamut from twitch action and fighting games to slower-paced games. I've played/tested many games on the 360 (HDMI), PS3 (HDMI) and Wii (Component), and the one game that I MIGHT have noticed lag was on Midnight Club: LA. It's completely possible it was in my head though.
I played Super Smash Bros Brawl with a friend of mine, and we've both logged many, many hours on that game on a CRT, and neither of us noticed, and we both were able to play as well as ever. I haven't even thought about the lag for weeks now. I bought a VGA cable for the 360 before the TV got here because I was worried about possible lag, but I haven't even taken it out of its bag.
About the screen glare/reflectiveness: if you're the type to be bothered by this, don't get this TV. The screen is quite reflective, even in fairly low levels of light. I don't really mind glare, so this isn't a big deal to me. Plus, the majority of the time that I use the TV is after work when it's darker anyway.
About image retention/burn-in: For the first 100 hours, I kept the contrast and brightness at 50, and didn't play any movies or games for over 2 hours that had any kind of static image or bars. I don't use any of the IR protection options like Orbiter, Color/White Wash, etc. I never had a single problem with burn-in during that period, and now that I'm over 100 hours, I've logged probably at least another 80 hours just using it how I feel with high brightness and/or contrast, and I still haven't had any problems with IR.
About the TV in general: it's fantastic. I really don't have a single problem with it. It looks completely gorgeous, even with default video settings. I'm extremely happy with this purchase. Incredibly sharp, deep blacks, bright, accurate colors.