Really interesting to see Automattic add this functionality.
It gives the app to access the user's WordPress data. Sites, posts, comments, taxonomy, a user graph, notifications.
Contrast that to what Dropbox offers -- access to users' files and folders. They don't provide a blog-like rendering of the data, as WordPress does. They've left that to developers, such as Small Picture (my company). What you're reading now, on Scripting News , was rendered from data stored in Dropbox. With Dropbox, the user has all their data sitting on their computers, synchronized at all times (the core feature of Dropbox). WordPress apparently offers no data storage other than access to blog posts and comments.
Google offers access to Google Drive data. No CMS features, but more flexibility with data.
Then there's Twitter, which gives you tweet-like renderings of very small chunks of data, with highly restricted write-access to large attached objects (pictures, video).
Will all these companies eventually even-out their feature sets and compete with each other in all areas? Will Dropbox provide blog-like renderings for data stored in the users folders? Google? Microsoft? Box? Will WordPress provide general data storage like app.net does?
It would be really interesting to see a full grid comparing the services.