As my former colleague John Kreisa nicely put in the HortonWorks 1.0 release announcement here (my warmest regards and best wishes to you guys!):
Those who have followed Hortonworks since our initial launch already know that we are absolutely committed to open source and the Apache Software Foundation. You will be glad to know that our commitment remains the same today. We don’t hold anything back. No proprietary code is being developed at Hortonworks.
And indeed. I have asked this questions about HortonWorks using BigTop to power up their platform offering some time ago and later pretty much repeated it in the form of comment to Shaun Connolly blog. To his credit, my question has been answered directly:
As far as BigTop goes, we at Hortonworks are using parts of BigTop for the HDP platform builds, so thanks for the efforts there!
I have meet the gentleman in person at the recent Hadoop Summit and we have a short yet nice chat about enterprise stacks and the role an open-source technology plays there.
So, it is time to put my initial question to rest as the fully answered one.
P.S. On a separate note: I have left a slightly different comment on Cloudera’ blog. Somehow, the comment doesn’t appear to be visible (at least I don’t see anything but “2 comments” line) nor had it been answered publicly (again, perhaps, it has been but I don’t see in on the page). In the Cloudera’s defense I have to say that I got an answering email from one of their execs, which I can’t publish for it was a private message.