According to various bits of evidence and reports, Amazon will be unveiling its own smartphone at an event later this week -- and the device may contain several differentiators.

The event, which the company has billed as "a launch event," is scheduled for Wednesday in Amazon's headquarters city of Seattle. In addition to journalists and analysts, a limited number of customers and developers have also been selected to attend if they made a convincing written explanation of why they should be there.

If a smartphone is presented, it will be the fourth line of hardware products from Amazon, in addition to its e-readers, tablets and set-top TV box. Because of its huge inventory of content, services and physical products, Amazon has been willing to lose money or break even on its hardware sales, gearing the hardware as devices to easily buy items and content from the company.

3D Tech?

According to reports, Amazon is also looking to release a phone with several key differentiators that could make it stand out in the crowded smartphone marketplace. One of the most often mentioned is 3D technology, possibly using four front-facing cameras to enable in-the-air gestural control. 3D tech in mobile devices is a hot area, with advanced research being conducted by Google and reports that Microsoft/Nokia will be releasing a 3D-equipped smartphone by the end of this year.

Avi Greengart, an analyst with industry research firm Current Analysis, told us that the indicators clearly point to a smartphone being released at the event.

He said the company released a pre-event video that showed "what looks like the top of a phone, so I think it's safe" to make that assumption.

Greengart also pointed to what he described as "very clever pre-launch PR swag" -- a children's book called "Mr. Pine's Purple House." The accompanying card said that the present was a childhood favorite of Amazon founder and CEO Jeff Bezos. The central lesson in the book, Greengart noted, is that "the world is a better place when things are a little different."

May Day Button?

In addition to positioning the smartphone as another entry point to Amazon's immense store, Greengart expects that it may also feature the May Day virtual button found on the company's Kindle Fire tablet.

When clicked, the button brings up a video chat with a service agent, ready to answer the user's questions or fulfill requests. Amazon, Greengart said, has reported that 75 percent of support questions for the Kindle come from the button, with what the company said was an initial response time after button click of under 10 seconds.

There have also been reports that Amazon will offer new ways for consumers to buy directly from its store, keeping extensive track of the user's preferences and needs. Amazon also asked any developers who applied to attend the event if they have experience in machine learning, so there is speculation that the smartphone may offer contextual shopping of a higher level than is commonly experienced.

Possibly as part of its preparation for the launch of the smartphone, Amazon has been working to boost the inventory in its app store. On Monday, it announced that the selection is now over 240,000 apps and games, almost three times as much as a year ago.