Patently Apple has release some juicy info on the next generation Apple iMac having a touch interface. These people have dug out new patent from Apple that indicated how they are going to use Mac OS X and iOS to come up with a multitouch iMac.
The next cool feature is turning the iMac into a tablet:
For example, an accelerometer in the display could sense the force of gravity along an axis, and the measured force could be used to determine an angle of the display with respect to the ground (i.e. the plane perpendicular to the direction of the force of gravity). A transition between input modes could be performed when the vertical angle (tilt) of the display crosses a predetermined angle.
In another example, a rotation sensor could be mounted in an adjustable stand of the display. The rotation sensor could measure a rotation position of the stand, such as an angle between the base of the stand and a hinged arm that connects the base and the display. The measured rotation position could be used to determine the orientation of the display.