The replies above are pretty interesting, but I still have questions. The article Optivity cited explains why many HDTVs don't properly display 24fps media properly. Now, I understand why that's relevant to watching most films, and it's something for me to look for when I'm shopping.
From what I can tell, however, plasmas don't seem to have any problems matching refresh rates in the 72hz range, and maybe even faster. However, from what I can tell, 3D displays will require even faster refresh rates: they have to present two video images, and it's desirable that each of these have a high refresh rate, too.
So on an LCD, a 120mhz refresh rate means that both signals will be displayed at 60hz; not perfect, and probably requiring some pulldown or other legerdemain, but perfectly serviceable. My question is whether a plasma would be capable of matching this performance.