> Yes.  Most mice, for example, though admittedly the Z axis support is
> minimal - typically only two positions are sensed.
What is often called the Z axis is just a wheel on the mouse.

> The core protocol has no support for more than two axes in the pointing
> device; it's full of structures with two fields for coordinates.  Look
> at almost any pointer event, for example, or the QueryPointer reply.
The mouse protocol decoder can map the Z axis to either the X axis, 
the Y axis, or button4/button5 events.  The latter can be put to good
use for scrolling up and down when the mouse wheel is turned.

        -- Lennart