Google grows more and more like Amazon with each passing month, transforming itself into an honest-to-goodness online shopping company, and this evolution is increasingly overt. But things got really cool today with the news that the web giant is posed to challenge Amazon with an army of robots.

In an excellent piece of reporting, The New York Times' John Markoff reveals that, led by the former head of its Android mobile operating system, Google is quietly buying up robotics startups for a project that appears more than just experimental.

"If Amazon can imagine delivering books by drones," Markoff writes, "is it too much to think that Google might be planning to one day have one of the robots hop off an automated Google Car and race to your doorstep to deliver a package?"

The difference between Amazon's drone stunt and Google's retail robot skunkworks, run by Andy Rubin, is that it seems far more serious. While Amazon released an unrealistic marketing video that had little to do with how its operations really work, Markoff's sources say that Google is taking incremental steps to automate steps all along the consumer-product supply chain, from manufacturing to shipping.

Delivery would seem to be the process where Google has made the strongest advances, though its self-driving cars predate Rubin's project. Speculation that autonomous vehicles would someday power Google's new same-day delivery online shopping service arose almost simultaneously with the announcement of the service itself. But delivery – the so-called "last mile" – is only one piece of the process that gets products from manufacturer to consumer.

All along the way, from factory to fulfillment center, technologies attempt to optimize the actions of human workers according to calculations made by computers. In other words, companies believe that the cent-shaving efficiencies they crave come the more they can get people to act like robots.

Amazon clearly understands this. Its $775 million purchase last year of warehouse 'bot maker Kiva Systems shows just how serious Amazon is about the advantages of automation. At the same time, Amazon still employs tens of thousands of people to pick and process orders in its massive distribution centers. The robot revolution has a long way to go, which means Google and Rubin still have a lot of room left to compete in.

And why wouldn't they? Amazon had more than $61 billion in sales last year. Its revenue exceeds Google's, though not its profits. Google is second only to Amazon among sites where people search for products online. With its paid product listings and Google Wallet digital payment system, not to mention its massive backend resources, Google has most of the bits in place needed to run a large-scale online retail operation. Now it needs the atoms.