Given Google's central role in driving e-commerce traffic through its huge user base, its move into real-world commerce could be a major game changer. An online shopping service that provides same-day delivery of food and other products - that's the basic idea behind a new service now being tested by the company.

Same-day delivery, a concept that bombed during the dot-com era of the late 1990s, is back on the loading dock. Major retailers such as Wal-Mart, Nordstrom, eBay, and Amazon.com are all offering same-day delivery in a limited number of locations. FedEx, UPS, and the U.S. Postal Service are partners in these pilots.