This week Amazon opened up its parcel shipping, fulfillment, and distribution "to businesses of all types and sizes." Any business can now ship, store, and deliver "using the same supply chain that supports Amazon," according to Monday's announcement of "Amazon Supply Chain Services." The move sent shares of UPS and FedEx "tumbling" Monday writes GeekWire . And though both stocks bounced back as the week went on, GeekWire sees this as the latest example of Amazon "turning its internal capabilities into products and services for sale..." "Amazon had already surpassed both carriers to become the nation's largest parcel shipper by volume, according to parcel-analytics firm ShipMatrix ." Initial customers include Procter & Gamble, which is using Amazon's freight network to transport raw materials; 3M, which is using it to move products to distribution centers; Lands' End, which is fulfilling orders across sales channels from Amazon's warehouses; and American Eagle Outfitters, which is using Amazon's parcel…