Plenty of info online.
60Hz vs. 120Hz vs. 240Hz - LCD Response Rate
Recently, manufacturers have introduced a 240Hz specification on some LCD TVs - some of which use the LED backlight manipulation as a mechanism which will produce an "effective" 240Hz "appearance" and others which state a straight out true 240Hz refresh rate. Some manufacturers TV models may claim "240Hz performance" and others 240Hz refresh rate. From our recent experience, a higher Hz rate in the panel produces a picture with less motion artifacts during fast motion and side to side pannning. 120Hz has less motion artifacts, lag, and judder than 60Hz, and 240Hz has less of the same than 120Hz. It's a marginal, not revolutionary improvement. In the end, these new specifications in performance allow the LCD manufacturers to mark up the product more while providing a new feature which is there essentially to make up for a serious flaw with LCD technology. It's the newest and greatest feature to convince you to upgrade. But consider beforehand how much sports programming and gaming you view when considering whether the feature is worth extra - especially in light of the need to turn it off for a majority of viewed programming.