Twitter Adds 'App Install' Card Types

Twitter Developers:

One of the most important features in the new Cards is the ability to allow users to download your app (if the user doesn’t already have it installed), or deep-link into your own app (if the app is already installed on the user’s mobile device).

Effectively, this is Smart App Banners for the Twitter ecosystem. By no means revolutionary, but it is a nice enhancement that helps to attract developer support for Twitter Cards. If you are an developer of an application that creates shareable content, there are much better incentives to integrate Twitter cards now, because conversions will be a lot higher with these additions.