taken from gizmodo:
When I first saw LCD TVs in stores and at exhibitions years ago, I was like, WTF? Why would anyone buy these? They were blurry as hell—couldn't everyone see that? Over time, the blur problem has subsided thanks to improved refresh rates of 8ms and less. But motion blur is not only caused by refresh rate, it's a natural problem that arises as LCDs flip from frame to frame, 60 times per second. The solution is to double the flipping, to 120 times per second, hence high-end "120Hz" LCDs hitting the market. We've talked about these sets when they were just launching. But there's new controversy as explained in this Home Theater Mag article right now.
As video editor Geoff Morrison's piece explains, part of the blur perception comes from the fact that, on standard LCDs, frames are frozen on the screen for 1/60th of a second, and then abruptly shift to the next frame. This is called "sample and hold." Other technologies like plasma and DLP don't hold the frame for that whole 1/60th of a second, but pulse from one frame to the next, with some healthy downtime. The obvious solution is to double the frame rate to 120Hz.
more indepth:
Home Theater: Motion Blur