Listings for both black and white versions of 16GB and 32GB “V3,” or third-generation, iPhones have appeared in the inventory system of UK-based iPhone retailer Carphone Warehouse. AppleInsider reports that the new listings appeared just hours ago, mixed in with listings for both iPhone 3G and original iPhone models. Many expected Apple to double the maximum capacity of the iPhone 3G to 32GB earlier this year, as it had done with the prior…