Phill actually wrote this today, so hopefully documentation is forthcoming.
My favorite gesture that has been in Clear “2” is the invisible back button: If you press above the white line at the bottom (I think it’s informally called the “Home Indicator”, but I’m not certain), it will go back. I’m not sure if it’s turned on or off by default, but it’s in Clear’s Settings in case you have it turned off. I think it’s so good that I wish other apps (and Apple itself!) implemented it.