Let me just state that I'm not speculating. I am basing this off of actual experience. For 3D movies, 24hz (times 2) at 1080p is all that is needed. I have a PS3 which I have hooked up to my 120hz monitor ( http://www.newegg.com/Product/Product.aspx?Item=N82E16824009300
It works great for 3D movies.
Games on the other hand, if I wish to use HDMI, require me to use 720p, which can support 120hz.