Circuit City, the nation-wide electronic retailer, is unplugging, and closing down all 567 of its American stores, including the one in the Shops at Midtown. Midtown has already weathered the loss of Linen-N-Things, and now Circuit City will leave another big chunk of unoccupied real estate. We held up Midtown as a bit of a microcosm of economic hardship back in November, and last week Frank Alvarado dug deeper into the mega-development's problems. Of course Midtown won't be the only strip mall