Well, they started with a gel-fitted Vivitar 285 flsh camera left--that is causing a bit of rim lighting along the side of the man's body. A very heavy vignette has been applied to the bottom of the frame--that lightens him up and gives some of that "embossed" look. The weather looks a bit overcast, and his eyes as you can see, are in deep shadow from the underexposure they did, probably to keep the sky dark and ominous-looking. The shot is basically a guy standing in a field, shot with a wide angle lens from a low vantage point, with a flash that is rim-lighting him. The fact that his eye sockets are totally black gives you an idea of how badly underexposed the shot was originally.
Without the yellow gelled flash coming in from the left, this shot would totally suck. It looks okay seen small, but I doubt it would hold up to even 8x10. If you open up the original size, you can see the effect of the un-gelled Canon flash. This effect is commonly called "overpowering daylight with flash", and cloudy,overcast days are the easiest to do this on,especially with most d-slr cameras. if you really want to learn how to do this effect, and shoot it a LOT, you'll buy a cheap Nikon D40 or D70 for its ability to synchronize flash at up to 1/8000 second with a flash hooked up with a PC cord and AS-15 or with a remote triggering system.
The web has many articles on overpowering daylight with flash. A cloudy day is easiest if your camera can only shoot flash at 1/200 second. The D40 and D70 being able to go as high as say 1/2000 second means you can make the sky look VERY,very dark and brooding, and make the subject "embossed" by lighting them up with flash, wile the background unnaturally drops off in intensity--all with basically no PS work needed.