Here's a lesser-known advantage that LCD televisions have over plasma: It's usually easier to hook an LCD TV to a computer. While LCDs have a long history as monitors for laptops and desktops, plasmas weren't designed to work with PCs and can be a hassle to set up.
So far, it has not been a big issue because only a small percentage of homes has tried to connect a TV to a computer, which hobbyists call an HTPC, for Home Theater PC. It will get more important as Hollywood productions increasingly move to the Web.
All kinds of devices have tried to bridge the gap between PCs in the den and the HDTV in the living room. All have shortcomings. I thought it might be better to hook an inexpensive PC directly to the HDTV. I'd get a roll-my-own TiVo for recording television programs and be able to download all sorts of entertainment from the Web.
Months later, I'm still fiddling with the setup. The first hassle was getting the PC to even work with our 42-inch plasma. It required a new video card that could output a high-definition signal. Even then, I had to download a geeky, $30 piece of software called PowerStrip to tweak the output to look best on the plasma.
I haven't tested one, but LCD televisions are said to work nicely with PCs. That's one more small advantage in the flat-panel fight, and one that could prove more important over time.