Web Intents provide popup-optimized flows for working with Tweets & Twitter Users: Tweet, Reply, Retweet, Favorite, and Follow. They make it possible for users to interact with Twitter content in the context of your site, without leaving the page or having to authorize a new app just for the interaction. Web intents are mobile friendly, and super easy to implement.
The whole screenshot is created with JavaScript. The only server interaction that is happening on this page is the proxy for loading the external pages/images into JSONP/CORS enabled page and onwards onto the JavaScript renderer script.