Yes, it appears that Amazon is bootstrapping this by using UPS to deliver packages to the store but there's a bigger vision at work here.
This is another attempt by Amazon to solve the "last mile" problem. Amazon already saves a ton of money on shipping costs by packing their own trucks and driving them from distribution centers (e.g. Fernley, NV) to major metropolitan areas (e.g. Seattle, WA) and depositing them at USPS for final delivery. Amazon could even remove this cost for those people who choose to pick up their packages at (essentially) Amazon PO boxes.
This is another attempt by Amazon to solve the "last mile" problem. Amazon already saves a ton of money on shipping costs by packing their own trucks and driving them from distribution centers (e.g. Fernley, NV) to major metropolitan areas (e.g. Seattle, WA) and depositing them at USPS for final delivery. Amazon could even remove this cost for those people who choose to pick up their packages at (essentially) Amazon PO boxes.