Okay, before you all start flaming me, lemme explain
I was at CC taking a final look at various sets before I bite the bullet. I was (and probably still am) planning to get a plasma. However, I believe that, in well-lit rooms, the glossy screen on plasmas lowers their 'effective' contrast, due to the reflection of ambient light, whereas LCD's don't have this problem to nearly the same degree, with their matte screens.
I was comparing a Panny 50PX75u right next to a Sony LCD. The former has 15,000:1 CR and the latter something like 7,000:1. Yet, the blacks on the Sony looked better, since the Panny screen reflected quite a bit of light. This was also the case for several other LCD's on display. The 42PX77U, with its anti-reflective coating was a little better, but the Sony still looked better.
If you'll be using the tv in a dark room, I'm sure plasmas look better, as far as CR. But if you have a lot of ambient light (even if it's not directly in back of you), you might want to consider this. The CC store was not very brightly lit and probably was similar to many residential rooms, as far as light.