This attribute means how "pointy" the geometry surface is, which allows to do
effects like dirt maps and wear-off effects on render geometry. This means the
attribute is calculated for the final mesh which means no baking (which implies
UV unwrap) is needed. Apart from this the behavior is quite close to how vertex
dirty colors works.
The new attribute is available as an output socket of Geometry node.
There's no penalty for the render time, only some delay on scene preparation
(the delay is linear of the mesh complexity).