AusGamers chats to Red Faction: Armageddon Lead Designer, David Abzug in video and transcribed form.
From the interview:
"For your viewers, the Magnet Gun is a weapon that takes whatever the first projectile hits and launches it at whatever the second projectile hits. So you can picture yourself, for example, grab this barrel and fling it at the wall, grab this explosive and fling it at the enemy, you know, but because we have destruction in our game you can fling half of that building, the top of the guard tower - you can fling anything man-made whether it's an eight-story building or a concrete barricade.
You can take out four or five bad-guys in one shot because you have launched a Seven-Eleven at them, okay."