Screen refresh rates on mobile devices
Since you are dealing with devices that have LCD screens (and not CRTs), it ultimately doesn't matter what the refresh rate is -- what matters most is how quickly a pixel can change from one color to another, and this isn't constant across the color range the device can display.

It is important how certain videos are processed since 24p can't fit into 60 equally (hence the supposed value of 120hz), but you'll find conflicting views as to if it is all that noticeable, useful, and/or even desirable. Let's just say this: I've never had a problem watching a video on my iPhone or iPad and noticing bad motion blur or odd artifacts.