Twitter has just taken the wraps off its media uploader API, which will allow developers to attach images to tweets.

In all likelihood, this API will also be used later on for uploading and attaching videos to tweets. Twitter hasn’t yet launched its own video-sharing features, though.

Just last week, Twitter launched its photo-sharing features to all users, a move that put it in competition with a few well-known third-party services, such as Twitpic and Yfrog. Basically, the new feature gave users the ability to upload photos alongside tweets with just a few clicks rather than complicated back-and-forth navigation and multiple sign-ins, making using third-party services a less attractive option.

But the launch of a new API for media uploading that Twitpic et al. will not only be competing with Twitter; they’ll be competing with any existing or new Twitter app that decides to use Twitter’s native photo-sharing API rather than integrating with Twitpic or Yfrog.

Many services in Twitter’s third-party ecosystem — and even Twitter’s official mobile apps — currently tap multiple photo sites to handle uploads and let users choose which service will host their images. However, the native API, which will eventually allow for photo and video sharing, will likely prove a more attractive option in the long run.

For starters, Twitter’s mobile apps will be using the new API, so any pics you share on Twitter from your phone will soon be uploaded through the Twitter photo feature rather than a third-party service.

The service was announced at the beginning of June. Back then, we speculated that Twitter’s new photo sharing feature might do some damage to these third-party, media sharing-specific startups. Now, we’re thinking the new media upload API might bury the startups entirely.

Of course, some devs are none too pleased with Twitter’s encroachment into the media-sharing space. In fact, Twitpic founder Noah Everett was so incensed by Twitter’s move that he launched a Twitter competitor last week.

“If Twitter can compete with its developers without fair notice, then why can’t we?” he told VentureBeat at the time.

However, it is Twitter’s prerogative as a business to control what gets posted to its service and how. Its behavior may not be fair, and it’s certainly not friendly, but it will keep more eyeballs on Twitter’s official properties and give Twitter more control over the media that flows across the service. And those two factors alone are good for business.

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