The scene at Facebook’s Hacker Way by David A. Kaplan @FortuneMagazine May 18, 2012, 10:33 PM EST E-mail Tweet Facebook Google Plus Linkedin Share icons FORTUNE — In the Alice in Wonderland-universe of Silicon Valley, realities can be deceiving. That fellow in a T-shirt and flip-flops is a billionaire and “We’re not in it for the money” means they probably are. So it was today at the headquarters of Facebook. That each employee and press flack declared “Today was just another day” pretty much confirmed it was not. Facebook FB finally went public, closing at $38.37, barely a Lamborghini above its offering price of $38. Most of the 2,000 or so employees here had spent the night at a “hackathon,” coding some future Facebook app or feature. Philz, the in-house coffee shop, opened at 5 a.m. for the bleary-eyed. The employees wore special gray T-shirts made just for the day. Emblazoning the T-shirts: STAY FOCUSED AND KEEP HACKING, even if the thought balloons over a few employee heads might have read NEW WINE CELLAR or SMALL YACHT! Never did the instantly recognizable huge blue “Like” sign that marks the entrance to Facebook look more appropriate. MORE: Rice Business Plan Competition: Hail to the champions At 6:30 a.m. outside and in front of almost every one of those employees, Mark Zuckerberg — co-founder, CEO, wunderkind of social media, and the richest curly-haired twentysomething on the planet — remotely rang the opening bell of the Nasdaq back in Manhattan. “All this might seem like a big deal,” he told his brigade of engineers and marketers. “But here’s the thing: our mission is to make the world more open and connected.” Big deal? Of course not! Unless you count as ordinary the minting about 1,000 millionaires and the creation of about $100 billion in the public markets. Social mission? No doubt. But there was also the thing about pricing your stock at the really high end — about 107 times earnings, raising $16 billion for the company. In a cordoned-off parking lot of the 57-acre campus of pastel-colored buildings that used to be home of Sun Microsystems, 10 satellite trucks — from CNN’s to Agence France-Presse’s — beamed out the latest updates on the stock price, with commentary from network stars. Journalists hoping to learn whether treasure was being counted inside learned from stray employees in the parking lot that they risked their jobs if they said anything other than “no comment.” Remarkably, on this day when risking your job was a particularly bad idea, most told me “no comment.” MORE: The draconian hidden penalty on student loans I did learn, though, many employees actually weren’t there, as the hackathon all-nighter left them exhausted and they went home. I did not learn whether they were on their way to check out $2-million fixer-uppers in Palo Alto — sorry, all-cash bids only — because at that moment a security guard pulled up in a pickup truck and urged me to go visit Google GOOG . Just kidding about Google. But I was informed that I couldn’t ask employees any questions. That rule didn’t apply the delivery guy from purpletie.com, which specializes in corporate door-to-door dry cleaning and laundry around the Valley. He told me today was a particularly light day. But he steadfastly declines to talk about Zuckerberg’s signature hoodies. By the time the stock market had closed, most of the circus had left town. The newscopters had long departed and the security guards had gone home. Around the Menlo Park neighborhood, some of it surprisingly rundown, few seemed to have noticed the celebrated event that had taken place at Facebook. But one fellow on the roadside apparently had a sense of humor. He was holding up a sign that said WILL CODE FOR FOOD. Who knows, maybe he’ll start a company tomorrow that in a few years will go public and itself make a fortune.