Peter Thiel, co-founder of PayPal and prolific angel investor, sparked controversy last fall when he announced a fellowship giving 24 young adults $100,000 over two years to leave college and pursue entrepreneurship full time.

The mission behind the program: Rattle the default assumption that every young adult needs a college education. Thiel thinks that rather than spend four (or more) years acquiring a crushing debt load, creative talents should instead go directly into enterprise: "an inquisitive mind, rigorously applied to a deep-rooted problem, can change the world as readily as the plushest academic lab."

The Thiel Foundation deemed the fellowship's first year enough of a success that Thiel has announced a second class of fellows.

Meanwhile, the inaugural class of young entrepreneurs has just about reached its halfway point.

"So far, they've really surpassed our expectations," said Thiel Fellowship co-founder Jonathan Cain. "It's been so rewarding getting to know the fellows over the last year, working with them, seeing them develop and grow."

Cain said that all 24 of the originally selected 2011 fellows remain active in the program. Neither Thiel nor the foundation has an ownership stake in any of the companies the grants help create (although several are revenue generating).

We asked five of the young founders to tell us about their experiences trading school days for the start-up lifestyle:

Gary Kurek

Progress report: After initially working on his preexisting company, wheelchair maker GET Mobility Solutions, Kurek realized he was overly bogged down with regulatory issues. He says his new company, which will involve hardware, software systems, and robotics, will launch soon.

Any revenue yet? None

Best takeaway: Pick your battles. "I realized that I wanted to be spending 90% of my time building technology and great products, and then 10% of my time with more bureaucratic issues, vs. the other way around."

College thing he doesn't miss: "The routine. I prefer to take the responsibility to plan my own schedule and take full control of my own life."

Dale Stephens

Progress report: Stephens founded an alternative-education site, UnCollege.org, and has written a book called Hacking Your Education that Penguin will publish in 2013.

Any revenue yet? Sort of: Stephens says he has brought in money (in the "mid-five-figure range") from speaking and consulting, and received an advance of nearly six figures from Penguin for his book.

Best takeaway: Take action: "You must know how to transition quickly from a learning-focused mode to a doing-focused mode. There's a much faster cycle to conform to."

College thing he doesn't miss: "The expectation that I have to do certain things 'just because.' I like to learn things because I see value in them."

Sujay Tyle

Progress report: Tyle is the VP of business development at a mobile social gaming company called Scopely.

Any revenue yet? None.

Best takeaway: Grow yourself, not just your company: "I've matured significantly through the fellowship. I've learned how to build and manage a team, and handle relationships in a business."

College thing he doesn't miss: "The structure. I think that structure can pigeonhole creative minds and put a limit on your ambition."

Andrew Hsu

Progress report: Hsu is CEO of an educational gaming company called Airy Labs that aims to make learning fun for children.

Any revenue yet? None.

Best takeaway: Grit your teeth: "In order to build a great company, there has to be a lot of sweat and toil put in--you can't be overly stuck on having a work-life balance."

College thing he doesn't miss: "Being stuck in such a hierarchical system."

Paul Gu

Progress report: Gu initially teamed up with another fellow to work on a local-commerce company called 404market, but he didn't feel inspired. Now, he says he's preparing to launch a company that will facilitate a person's investment of money in another individual (for example, one person investing money to help another go to grad school).

Any revenue yet? None

Best takeaway: Make a difference: "I realized through the fellowship that I needed to work with something that appealed to my intellectual interests but that also felt like something that could really help people."