New this build: a new File Chooser plugin, some built-in gestures in the Touch object, a new Preview Effects editor option, and lots more!
File chooser plugin
The new File Chooser plugin shows a Choose File button that lets the user pick a file from their local disk. On mobile you can also either choose a file from the device documents or a file storage app like Dropbox, or use the device camera to take a picture and use that as a chosen image file. (Exactly what options are available depends on the browser and OS.) It's supported on all modern browsers, but for IE only on IE10+.
Once a file is chosen, you can retrieve its filename, size in bytes, the MIME type (e.g. image/png for a PNG image or text/xml for an XML file), and the file URL. Despite the fact it's a local file, its data can still be accessed by the given URL (which is usually "blob:" followed by a unique ID). For images you can display the chosen file using the Sprite object's Load image from URL action, or (perhaps less obviously) you can AJAX request the file URL like any other URL to get its text data.
This allows you to make use of local text and image files, which could be useful as an alternative for showing photos other than snapshotting a video feed in the User Media object, or allowing a way for text, XML or JSON content to be loaded from disk.