Uber announced on its blog on Tuesday that it is launching a test of a new delivery service called Cornerstore. Uber users in the Washington, DC area will see an option in their app to order from a list of 100 household items. If an Uber driver is available, the goods will be picked up and delivered to their door. There is no charge, no expectation of a tip, and no minimum purchase. It’s one of many ambitious delivery services from tech companies big and small that have come online in the last few years, all of which seem, on the face of things, too good to be true. Uber is careful to stress that the Cornerstore operation its launching in DC is just a test. But the company and its investors have been openly discussing for some time Uber’s ambition to use its fleet of drivers for more than just ferrying people between point A and point B.