To use the feature is simple: write your tweet normally. Then, realize that a camera icon appears below the text box. By clicking here, since the operating system loads the dialog to choose the image that goes to Twitter's servers.
Tweeting the message, the picture is presented by the link that begins with pic.twitter.com. That is, since the implementation of the resource, the new official address of Twitter for image storage.
When a user clicks on the tweet, sent the image appears with the message in the right sidebar (I'm talking about the web interface of the service, which is final and binding as long yesterday). If the link is accessed directly, the user reaches a page that contains the tweet (with a font size than needed, who knows why), sent with the image below.
The question remains: what will happen to third-party services that offer the same functionality? TwitPic yFrog and has, just to name the best known. Many others are available in this great network - just look at the various options that are presented to clients like TweetDeck.
This change was expected. When iOS 5 was first introduced, Apple has shown that a special integration with the microblogging platform had even upload images without relying on external service. Now we have the result of this decision in the web interface for Twitter.
I liked it. I think that makes life easier. And you?