I use it with the same polar image distortion as mtmckinley said.
Just grab your HDR image, or HDR sequence, or any decent image with decent white and black point vlaues, and map that to RealFakeGI's color or ambient color and you're good to go
Then, connect the Real Fake GI output to your shaders ambient channel
Make sure your lights ONLY cast shadows.
Otherwise, it messes up your overall light intensity.
(though, sometimes it's not a big deal)
Global Illumination is all around us, inside and out.
If you use it when you render spearate passes of specular, diffuse, etc. it comes in REAL handy for that added extra touch of realism
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS