The reflection map applies to the reflection node of your object, 
just like a texture map on other nodes.  The difference is that the
reflection holds still in space when you move or turn the object,
so that the ground always reflects onto the bottom of the object
and the sky always shows on the upper part of the object.

So they probably mean that the reflection 'surrounds' your objects
*as if it were a sphere, * not that the sphere is actually in the scene.

(In other words, the term 'virtual' is being used in its original sense
of a truly imaginary object.  As opposed to our normal use of 'virtual'
to mean something that is 'real' within the Poser world.)

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