I've compared notes with successful and unsuccessful candidates, and this is the best I can offer about Joyent's interview process:
* they hire almost entirely on reputation; successful candidates remark that their credentials and capabilities are not meaningfully scrutinised in the interview process and that, given Joyent's reputation for a surpassing technical culture, they are somewhat surprised that the interview questions are easy
* reputation is established based on two, possibly three things: 1) work on upstreams that matter to Joyent, where they can see sustained contribution and quality; 2) previous work with Joyent staff, generally on the same teams; and possibly 3) reference from someone with whom they've worked directly and rate highly (note: I'm speculating on the third, I've only seen the first two have impact)
* the interview process isn't so much about a fit for ability as for interest and process: specifics of substantial development efforts are already public, as is their engineering workflow
* first interview is fairly loose, provides instructions on materials to review for second interview
In short, while there are clear means of screening false positives and false negatives, they have very little to do with the interview process proper.
My experience was that I was socially familiar with Joyent people but had worked in a position that didn't quite give me credentials I knew they preferred. Although we were direct about this in the first interview, and I was told I had a second interview, it never happened. At great length.
Was asked to do a coding assignment. Returned assignment, asked to proceed with second interview, and hemming and hawing started. I was able to determine exactly when they looked at the coding assignment, and six weeks passed with e-mail exchanges while the code was completely ignored. First red flag. Hiring manager acknowledged that he had forgotten what understanding was reached about prep at the end of the first interview, hadn't taken notes. Second red flag, as assurances given, recall of credentials also possibly out the window.
Did a fair amount of prep work on expectation of second interview. When two months passed after the first interview with none scheduled, I sent a suggested technical discussion agenda reflecting prep. I can only characterise the responses as filibusters: they didn't really make sense as a response to what I said but looked like an attempt to convey reservation, certainly conveyed greater failures of recollection. Third red flag.
At the same time, I was explicitly told I was still under consideration and that "we" needed to work through concerns. Never clear how, if not by interview. Asked to look at a "puzzler". Fine, except that it wasn't particularly clear that the format allowed for meaningful evaluation (answers and reasoning were already largely available in the blog post, as is part of the puzzler format). Sent response, never heard back from hiring manager.
Three weeks passed with no further word, wrote them off. Weeks after that, recruiter, who never responded to mail except to set up first interview, sent mail saying nice things but finally "no".
Three months of dragging filibustering to renege on a second interview commitment is a distinct lack of courtesy. Such courtesy does not seem an unreasonable expectation: I was an employee referral, have referred business to them, etc. Other candidates with whom I've spoken have been told directly about hiring preferences, although ghosting seems a pathology.