We already pretty much knew this :p We've had a lot of 1920x1080 screens from Nintendo over the last few months, and smash has always targeted 60fps. It being a fighting game also made it rather likely. Street Fighter IV managed 720p/60fps back in 2008.
That said, i'll props to them if they can maintain a solid 60fps during 8 player battles and with the camera zoomed out. Would be quite impressive for the WiiU.