Without a formal announcement, Amazon.com has started allowing authors made it easier for authors to publish their ebooks for the Kindle with or without digital rights management (DRM), the technology that limits how consumers can use the ebooks they’ve bought. [See update below.]

The change appears to have gone in effect around Jan. 15, when a few Kindle publishers spotted changes in Amazon’s Digital Text Platform. A new option gave publishers the choice to “not enable digital rights management.” A science-fiction author named Joseph Rhea appears to have been the first to notice the change. On Jan. 15, Amazon announced an expansion of its Digital Text Platform to non-U.S. authors, but made no mention of DRM changes.

Amazon’s brief explanation of the new feature inside the DTP:

You may choose, on a per title basis, to have us apply DRM (Digital Rights Management) technology which is intended to inhibit unauthorized access to or copying of digital content files for titles. Once your title is published, this setting cannot be changed.

The Digital Text Platform is aimed at small publishers and authors; it’s gained a foothold in short fiction, but it’s a platform with potential for both independent journalists and small news organizations. It’s unclear whether similar changes are afoot for newspapers, magazines, or large publishers, who use a different system to publish to the Kindle. I’ve asked Amazon for explanation of what exactly this new choice entails and haven’t heard back. I’ll update this post if I do. [See update below.]

Many book publishers (with a few notable exceptions) have been hesitant to offer their works digitally without DRM, fearing a “napsterization” of their industry — a free supply of all books available for download via file-sharing networks.

But eliminating DRM could also increase customers’ comfort level with buying ebooks. Right now, someone who buys lots of Kindle ebooks is out of luck if, six months from now, some better non-Kindle ereader comes along. The books can’t be moved over. Without DRM — and with the knowledge that their ebook investment can have long-term returns — readers might be willing to shift their buying to digital. That may or may not be good news for publishers — their margins are higher for hardcover books than for ebooks — but it would be good news for Amazon, the dominant ebook vendor and one that has shown willingness to expand the Kindle platform beyond the Kindle device.

It’s hard to ignore that Amazon is making these changes shortly before Apple is expected to unveil its long-anticipated tablet computer on Jan. 27, which could be the most potent challenge to the Kindle ebook ecosystem yet. Amazon also announced yesterday it would radically improve the revenue share it offers Kindle publishers, handing over 70 percent of the list price — a level that matches what Apple offers software publishers in its App Store.

We won’t find out until next week what DRM restrictions the notional Apple tablet would offer. Last year, Apple removed DRM from the music it sells via iTunes, but it remains on iTunes’ movies and TV shows.

While most big publishers seem unlikely to step away from DRM anytime soon, some of the independent authors who have used Amazon’s DTP to self-publish were more excited about the move. As research scientist/”hobby” writer Joseph Rhea put it:

I can only speak for myself, but I know I would be happy with someone buying my book and sharing it on 2 Kindles, or a Kindle and a PC (with the Kindle reader), or your iPhone. It’s yours, so why shouldn’t you be able to read it anywhere you want? I am also not that worried about people “stealing” it and making thousands of copies that are spread all over the web — I should be so popular!

UPDATE, 5:18 p.m.: Amazon just got in touch to say the change is not about allowing DTP users to publish without DRM — it’s about making it easier for publishers to choose DRM or no DRM. The choice has always existed for DTP publishers, a spokesman said, and the default state was no DRM. (That’s different from the situation with larger publishing houses, where anti-DRM publishers have complained about the difficulty of removing “Kindle’s ‘compulsory DRM.’”) I updated the headline and lead to reflect that.