What does dynamic contrast mean for a plasma?

[AlexMcIver]

I noticed on the Panasonic website that the contrast ratio was quoted as 30,000:1 (1,000,000:1 dynamic). For LCDs dynamic seems to mean that they dim the backlight on dark scenes to give a perceived increase in contrast. However, plasmas do not use a backlight so this can't be the case. Is this just marketing drivel or have they found some way to massively reduce precharge glow in certain circumstances?

 

[sampo]

Basically floating blacks:

http://www.youtube.com/watch?v=vF3hOyNZ3rg
Panasonic PX70

 

[badbob]

That's horrible.