Two developments this past week signal that Wal-Mart is getting more serious about the online world, and could very well have Amazon.com in its crosshairs. On Saturday, Wal-Mart began testing a new home grocery delivery service in San Jose, California called Walmart to Go.

As many Seattleites already know, Amazon.com has been developing its own version of home grocery delivery in Seattle since 2007 called Amazon Fresh. At this point, Amazon has contained the trial to Seattle as it works out the many logistical kinks associated with the business. (traffic patterns, delivery windows, etc.)

However, with Walmart dipping its toes into the market, could we see Amazon Fresh trucks start to roll in other markets?

It is certainly a possibility, though home grocery delivery is a complicated and tough business as players such as HomeGrocer.com and Webvan have already discovered. Stay tuned.

The Walmart to Go launch comes amid a deeper push by the Arkansas retailer into the online world.

Last week, the company purchased Kosmix, a social and mobile commerce startup led by Venky Harinarayan and Anand Rajaraman. Those names should be recognized around these parts. They sold their previous company, Junglee, to Amazon.com 1998.

As part of the acquisition, the former Amazon.com employees have been charged with helping to lead Wal-Mart’s newly-formed Silicon Valley research operation, @WalmartLabs. The company offers this explanation of the new entity:

Walmart plans to expand the @WalmartLabs team and expects this new group will create technologies and businesses around social and mobile commerce that will support Walmart’s global multi-channel strategy, which integrates the shopping experience between bricks and mortar stores and e-commerce.

Wal-Mart and Amazon.com have not always been the best of friends. In 1998, Wal-Mart sued its Seattle rival for allegedly violating trade secrets through the hiring of several key Wal-Mart employees.

The latest chapter in the rivalry will be interesting to watch, especially as Wal-Mart looks to take advantage of its physical retail presence and marketing power in 15 countries.

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