-fluke
LCD's and plasma displays don't have a refresh rate due to the fact that the pixels are dictated by direct electrical current through dedicated transistors, and not by a scanning electronic beam that 'refreshes' the screen at a certain frequency per second.
The pixel information changes as needed with an LCD because there is no electron beam it has to wait for to display the change on the next sweep.
This is why one's eyes tend to not get as tired as quickly with an LCD - no flashing.
The closest thing to a refresh rate would be dictated by the speed of the GPU - how fast can it get the pixel information to the transistors in the display, ergo the distinct advantage of a digital feed: The GPU controlls the screen directly without having to wait for digital-to-analog-to-scan conversions as well as the afore-mentioned refresh rate.
I hope that helps.
(edit) the only time I've heard of an LCD refresh rate even mentioned was with machines who feed their LCD's with an analog signal. A number of Gateway machines do this, like the Profile 4.