An application programming interface (API for Twitter) is an interface implemented by a software program to enable interaction with other software, much in the same way that a user interface facilitates interaction between humans and computers. APIs are implemented by applications, libraries and operating systems to determine the vocabulary and calling conventions the programmer should employ to use their services. It may include specifications for routines, data structures, object classes and protocols used to communicate between the consumer and implementer of the API. Twitter button
The Twitter micro-blogging service includes an API that gives RESTful access to the Twitter database and activity streams (users, tweets, friends, followers, favorites and more), using XML and JSON formats. Twitter bar
APIs are Biz Dev 2.0, as Caterina Fake put it, our ability to connect Tweetie 2 to WordPress.com proves this out. We didn’t have to talk to Loren Brichter because he built custom API support into Tweetie 2 — thanks Loren! (As an aside, I’d love to see custom API support added to TweetDeck and Seesmic, my two favorite desktop Twitter clients.)
There are still some rough spots around the edges but the core posting and reading bits of the API are solid and the rest is coming soon. I see the Twitter API as one of the new de facto standards that as many applications should support as possible. Twitter mobile
(Amazon S3 API too, why don’t all cloud storage providers use that?) We’ll be open sourcing the server as a WordPress MU plugin, so that other people can take advantage of our work and benefit their readers and communities.
Since such a big part of the Twitter API is around reading other blogs, and your self-hosted WP doesn’t support that, it’s not a great experience yet. If mainly what you want is ease of posting I’d suggest checking out the WordPress iPhone client or the post-by-email features.