Announced many months ago and only now becoming available, Incipio's Destroyer Ultra for iPhone 4 ($28) has been hugely redesigned from the company's original concept. Now simplified into a rubber inner shell with a single snap-on rear plate that combines hard plastic and a textured rubber grid, plus a hard plastic belt clip with 360-degree rotation in 45-degree ratcheting positions, Destroyer protects the iPhone 4 with plenty of plastic on every…