The details, unfortunately, are scant. This is what we know:

Amazon, the world’s largest Internet retailer, will be launching an online streaming video service in the next several weeks, Amazon CEO Jeff Bezos said a little too matter-of-factly at the D: All Things Digital conference. (Reuters)

One detail: The streaming service will start immediately for viewers, unlike Amazon’s Unbox product, in which users are required wait a period of time as content downloads.

Another semi-detail: The streaming service will operate a-la-carte, but we don’t know what this means exactly. Can viewers stream movies on a pay-per-view basis, presumably at the industry standard $3.99 per rental? Or will this service operate ala Netflix, where people pay a monthly subscription fee (like $15) for a certain number of movies?

We’re sure additional details will be forthcoming in the coming days, or weeks.

The one thing that’s clear about Amazon’s move is that the retailer is beefing up its digital media offerings in order to compete with rivals Apple (iTunes rentals and purchases, AppleTV, portable media players like iPod Touch), Netflix (rentals via mail, online streaming, the Netflix/Roku set-top box), and others in this crowded, competitive space.

Also see: Amazon in your living room: today and in the future

Besides the online streaming service, Amazon has the video download service Unbox, an agreement with set-top maker TiVo (so downloaded content can be watched on TVs, not computers), the digital music store (AmazonMP3), and the electronic book reader Kindle.

So when the time comes that digital distribution is dominant, Amazon is ready.

[A slight update from Silicon Alley Insider: It’s a pay-per-view service similar to the existing Unbox. “The only difference is the delivery/storage method, and the fact that you can watch movies right away — instead of waiting for them to download.” No word on if the service will work on Macs, unlike Unbox, or if they’ll be a tie-in with TiVo.]

[Photo credit: Asa Mathal at AllThingsD.com]

AllThingsD, Amazon, Apple, Netflix, TiVo