AT&T has announced that it will accelerate its rebranding campaign at Cingular wireless stores to better take advantage of the iPhone’s launch. The company will replace the Cingular name with new AT&T signage in the interior its 1800 shops, ahead of the iPhone launch in late June. “The iPhone is one of the most anticipated handsets ever in the wireless industry, and we want to make sure that every drop of equity from the iPhone…