Never heard of that cut either but whatever you call it it sure looks yummy.
Odd just as I was typing I am watching iron chef and sure enough one of the gus is cubing up a flat iron steak.
Gott go google it.
From Wiki:
The Flat Iron Steak is a cut of steak from the shoulder of a steer. The design of the cut of steak was created by researchers at the University of Florida and University of Nebraska during the course of a study of undervalued cuts of beef. The study also found that this specific cut is the second most tender cut of beef, after the tenderloin. The major initial barrier to the flat iron steak was the large band of connective tissue running down the center of the steak, which led people to assume that the cut in general must be tough. Removing the connective tissue, however, leads to a steak that is often described as having both the tenderness of a rib eye or strip steak while still having the full-flavored character of a sirloin or skirt steak. Whole, this muscle is known as Infraspinatus, and one may see this displayed in some butcher shops and meat markets as a "top blade" roast. Steaks that are cross cut from this muscle are called top blade steaks or patio steaks. As a whole cut of meat it usually weighs around 2 to 3 lbs, is located adjacent to the heart of the shoulder clod, under the seven bone. The entire top blade usually yields 4 steaks, between 8 to 12oz. each.
Restaurants, particularly upscale, have recently begun serving flat iron steaks on their menus. Especially popular are flat irons from Wagyu beef, as a way for chefs to offer more affordable and profitable dishes featuring Wagyu or Kobe beef.