Combining multiple types of media into a list and treating it as a document is at least as old as multi-part email, but a more recent trend is making this structure explicit to the user and incoporating it into the editor. Naver Matome is the ultimate expression of this - a post is just a series of sections, where each section is a link, a quote, an image, or one of several other types. Other familiar examples are Tumblr blogs (where each post has a multimedia type) or the Medium editor.
Some of these list editors focus heavily on simply collecting existing content; examples include the ill-fated Delicious stacks, Streme, and Pinterest. Others emphasize stringing together documents from multiple sources as part of illustrating a larger story; examples include Matome, Storify and its many clones, and Togetter (Japanese, Twitter focused). Many of these sites describe themselves as "curation" services.
There are open-source tools for making editors like this as well, such as Sir Trevor. The Smallest Federated Wiki uses a JSON format based around typed blocks. Jupyter (formerly the iPython notebook) also uses typed blocks in their editor, though the blocks are mainly not-code (Markdown/HTML), code, and code output rather than being multimedia-oriented.
Lists of content as a kind of artifact of their own reminds me of the concept of "trails" from As We May Think, particularly as described in section 7:
The owner of the memex, let us say, is interested in the origin and properties of the bow and arrow. Specifically he is studying why the short Turkish bow was apparently superior to the English long bow in the skirmishes of the Crusades. He has dozens of possibly pertinent books and articles in his memex. First he runs through an encyclopedia, finds an interesting but sketchy article, leaves it projected. Next, in a history, he finds another pertinent item, and ties the two together. Thus he goes, building a trail of many items. Occasionally he inserts a comment of his own, either linking it into the main trail or joining it by a side trail to a particular item. When it becomes evident that the elastic properties of available materials had a great deal to do with the bow, he branches off on a side trail which takes him through textbooks on elasticity and tables of physical constants. He inserts a page of longhand analysis of his own. Thus he builds a trail of his interest through the maze of materials available to him.