Michael Novelo provides a look at employing IES Lights in Blender and rendering in Cycles, with an overview covering what IES lights are, where data files can be obtained, and also covers how to use the Import IES Lights Blender Addon.

This Video Tutorial is about how to import and use IES lights into Blender

Recently there became a Blender Addon written in Python adding the ability to use and render IES Light profiles in Blender Cycles. The ies2cycles.py imports and can use photometric IES lights right in Blender Cycles Rendering engine, and Michael also takes a look at rendering the IES profiles in Cycles using the tool.