The new Apple MacBook allows users to interact with the touchpad with multiple fingers.
If you drag both fingers down it recognizes both fingers and scrolls the page like a mouse wheel.
If you tap with one finger it's a normal click but if you tap with a finger already on the touchpad then it's an option click. These basic tricks are novel and interesting but the ability to interact with multiple fingers creates the potential for much more natural interaction models for the OS and for application developers.
Multi-point interactions:
- Rotation - rotate objects on screen with the turn of your wrist. Rotate both fingers in a circle.
- Scale/Zoom - move your fingers out from the center or back in to the center.
- Crop a photo - mark the top left and the bottom right corners with both fingers
- Virtual Scratchpad in a music player - spin the record up and down with multiple fingers
- Resize or move an application window with both fingers
- Continuous scrolling - Let your fingers do the walking
A lot more is possible. It'll be interesting to see what app-developers come up with.