This is not a fake: the US army really uses some HMMWV in iraq with miniguns attached to them. See this video and hear how fast a minigun shoots in real life (a LOT faster than it looks in video games (like Battlefield or Armed Assault) or movies).

This is a very impressive and shocking video.
Iraqi insurgents (or better: terrorists) try to kill the soldiers in a patrolling HMMWV. The IED (Improved Explosive Device) was placed below the asphalt. When it explodes, you see that the explosion is strong enough to ruin the street, but luckily it is not big enough, to harm the soldiers in the HMMWV.

The camera of a soldier is set directly behind the front window.

Anti-Air HMMWVs:

A very new system is the Avenger "modification" of the Humvees. It's an anti-UAV/anit-air system.

The Avenger is an anti aircraft syste, based on a HMMWV maintained with 8 stinger rockets. Now the US army tested a modified Avenger system: it is a HMMWV that carries a laser with a power of 10 kW (kilo watts).

The test was successful, three UAVs were destroyed.

Here is a german video about the system:
http://www.spiegel.de/video/video-50784.html