A fellow in Montana who identifies himself online as either "SOC" or "pfcthiel", and who has no compunction about posing in front of a Barney Fife flier, has created a "Firearm Mounted Anti Zombie Device", presumably without any knowledge of Gears of War.

He posted pictures of his gun+chainsaw combo in a thread on a gun fan site with the following text:

What stuff you guys want to see it cut? (Note: I am on a $50 budget for stuff I'm cutting)

There are also videos of his invention in action. For instance, here he gets the jump on some pumpkins (much to the delight of a nearby heavy smoker). Here he demonstrates how you can get through a locked door (provided the door is constructed from dried out balsa wood). Here he does some light yard work.

On YouTube he offers to build you a Firearm Mounted Anti Zombie Device for about $300, but I'm guessing you have to supply your own AR-15 semi ("Don't call it an assault rifle!") automatic.

Thanks Giant Bomb!