I'd say that is unlikely. The two other instances of reports of seeing the file format pre-date Creative Cloud by several years, and both were seen when dealing with Data Merge.
I suspect it may be a diagnostic tool that is meant for access by the Adobe Engineers, and we've inadvertently found it by mistake.
The only other reference I can find is for Adobe Connect http://help.adobe.com/en_US/connect/9.0/using/WS11d1def534ea1be08a52b610b38bfaa95-7f53.htm l
Where creative cloud file storage is new, I remember Adobe trying to push other Adobe Connect file sharing for reviewing pdfs etc. in the past, even before CS5.
I'm maintaining that the issue is unrelated to the Adobe Cloud system.
I say this because looking at the ADCF file that was generated from InDesign (it's back in my first post) it is relaying information about the file I used as the data source in my Data Merge file, but nothing else about the document.
There is also the link to the post from John Hawkinson (again in my first post) that is similar in nature to the scenario I had when discovering the export option by accident.
Because this is a user to user forum that is occasionally visited by the Adobe Staff, I'm hoping that an Adobe staffer will see this and be able to shed some light on this enigma.