On the plasma burn-in issue...
It's true that it's really hard to get permanent burn-in on a modern plasma, but temporary image retention might be more of a problem than plasma fans will tell you. I have a fairly new 42" Panasonic plasma, and I follow the rules - I set the pixel orbiter to the highest frequency, I ran the 200 hour break-in (actually did it for 10 days/240 hrs), and even after having done so I still keep the brightness & contrast low. Unfortunately, I currently play Gears of War 2 about 2-3 hours a night. For those who don't play it, the game has a HUD in the upper right corner showing a white silhouette of your currently selected weapon and ammo level on a black background.
I can often see a faint shadow of the HUD when I'm watching TV or movie scenes with a light (especially white) background; I can only make it go away after a couple of days of watching TV while avoiding Gears, but it does eventually disappear. Running the screen wipe doesn't do a whole lot. It doesn't totally ruin my viewing experience or anything, and my girlfriend says she rarely notices it, but I can see the shadow and it bugs me. If you do a lot of gaming with static images you may get noticeable image retention, even if it doesn't burn in.
Before I bought the TV, people told me I'd never experience anything like this if I ran the break-in ritual; now, I'm hearing and reading that I have to pass 1,000 hours on my TV, and then I won't get any more persistent image retention. We'll see. I kind of wish I had gone LCD - I really love the plasma's picture, but I wouldn't mind a TV I could just use without having to think about these things.