From A List Apart website:
Touch introduces physicality to designs that were once strictly virtual, and puts forth a new test: How does this design feel in the hand? Josh Clark guides you through the touchscreen frontier. Learn about ergonomic demands (and rules of thumb), layout and sizing for all gadgets, an emerging gestural toolkit, and tactics to speed up interactions and keep gestures discoverable. Get the know-how to design for interfaces that let you touch-stretch, crumple, drag, flick-information itself. It's in your hands.