If there's one downside to internet shopping, it's that you don't get the immediate gratification of having an item in your hands the moment you buy it.

But if eBay has its way, you could at least get some of your shiny new purchases within a few hours.

The auction site has partnered with retail giants like Target, Toys "R" Us, Walgreens, Nordstrom and Fry's Electronics to offer eBay Now, a same-day delivery service accessed through a special mobile phone app.

Currently it's only available to customers living in San Francisco, but eBay hopes to roll it out to other major cities in the coming months. The service is seen as an effort to do battle with Amazon, which has been building warehouses all over the country and prompting many people to wonder whether it's about to launch its own same-day delivery feature.

But since stores already have their inventories uploaded onto eBay's online marketplace, it won't need those pricey warehouses -- and that could provide a huge advantage.

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