Last night, Nightline featured Carl's Jr.'s limited release footlong cheeseburger in a segment called "Sign of the Times." Aside from the footlong cheeseburger, they also mention KFC's Double Down, Friendly's cheeseburger melt, and Denny's fried cheese melt as examples of chain restaurants trying to "out-calorie, out-fat, and out-gross each other."

If you're a regular AHT reader you're probably familiar with the latest developments in the megaburger/sandwich world, but for the rest of you, here's your primer. Watch the video after the jump.

Burger Wars Salvo: Foot-Long Hamburgers