Short version: Its possible to teach a person to write a simple ruby crud app in 9 weeks. This roughly mirrors the first semester college class. Many companies need that. The trick to getting them hired is to get lots of people with entry level skills in a room with lots of companies that want entry level people.
As mentioned in the wikipedia article for dev bootcamp (emphasis mine)
They're working on Rails (which is reasonable for CRUD apps), and a few basic bits of markup. Its designed for someone who has no experience in programing or familiarity with learning how to learn a programming language.
tuition costs are $12,200 for the 9 week, 40 hour per week program. Although traditional class hours are 9am-6pm on weekdays, most students stay nights and weekends, which amounts to an approximate 70-80 hours per week
... well I know what my next job will be.
The key to the results is not the training. And quite frankly, if the person doesn't have the right mindset to learn how to program or the curiosity to do more and better - they'll remain forever at entry level. There is a call for that (in some markets there is a lot more openings than people filling them - which brings us to...)
Another point to consider when they advertise the average starting salary, one needs to look at salaries. For example in San Francisco the median pay for a person who sits at the front desk and organizes mail is $52k, and the person who sits in front of a director or C?O and does the same is $62k. A software engineer has a median salary of $93. $85k is not a lot in San Francisco. (see also cost of living in San Francisco - seriously, the rent in SF for a year is more than many people make elsewhere in a year) Similar things can be said of Chicago.
Dev Bootcamp organizes hiring days for technology companies to interview students. They then collect a referral fee from employers that hire their graduates, and they pass along part of that fee to the graduate in the form of a hiring bonus.
The key to getting people hired is getting them face time with the various companies. Its the connections in this case - of the recruiters who want the front line of coders and the dev bootcamp organizers. This can also be done outside of a boot camp (give your information to a head hunter - they have similar access).
The dev bootcamp is unlikely to get into data structures (its fortunate that Ruby has so few), nor various parts of theory that helps one write better code. They are teaching people to write simple applications. There are many times when companies are just after simple applications.
How well these applicants do long term is yet to be seen - dev boot camp was founded in 2012. Many of these students and new hires haven't even had their first year's performance reviews yet.
I will point out that this is based on dev bootcamp itself which is in SF and Chicago, and information relating to the skilled programer job market in those two cities. The job markets in other regions of the United States or other nations is beyond my familiarity.
It is important to engage existing career finding resources (like headhunters and friends who can get a referral bonus for giving a resume to HR). All of this is for naught if the market is over saturated with people looking for jobs (it is in some areas).
Going to such a class and expecting to find an $85k job afterwards in rural Montana won't happen.