Any details on the approach they used? In my experience, it's impossible to beat css3 transitions on a platform that hardware-accerelates them (i.e., only iOS as of this writing)
He said they use horizontal scrolling to slide the page in from the side. I haven't yet dug into it to see how they're doing it, so unfortunately I don't have any more details, but you can download Sencha Touch 2 and check it out.
I guess the difference comes from using -webkit-translate3d which kicks in hardware acceleration instead of -webkit-translateX or simple -webkit-transition.
