Facebook is now officially a public company as it made its shares available for trading on the Nasdaq this morning priced at $38 a share. This gives the social network a potential market cap of $104 billion for the largest Internet IPO in history.

CEO Mark Zuckerberg rang the opening bell from Facebook headquarters in Menlo Park, Calif. Employees spent all night on the company’s 57-acre campus for a hackathon event where they worked on new projects of their choosing. The hackathon seemed aimed at keeping employees focused on Facebook as a product rather than Facebook as a multibillion dollar company. To the right is one of the posters from the event.

Zuckerberg, who created Facebook in 2004, put off an IPO for years in favor of focusing on growing its user base and implementing sometimes controversial but largely transformative features. These include News Feed, Facebook Connect, Instant Personalization and the ill-fated Beacon, which has been ultimately re-imagined as Open Graph with far more success.

In 2010, Zuckerberg made his perspective clear in a response to a Facebook Question about when the company would go public:

“I tend to think that being private is better for us right now because of some of the big risks we want to take in developing new products. [...] The experience of managing the company through launching controversial services is tricky, but I can only imagine it would be even more difficult if we had a public stock price bouncing around. There are a lot more new things left to build [...] and I’d rather focus on building them than on going public right now.”

Among those features turned out to be an expanded Credits program, single sign-on for mobile devices, a mobile app platform, Sponsored Stories, asymmetrical relationships through Facebook Subscribe, a unified messaging system, new groups and list features for small-group sharing, location tagging for all posts, Timeline and Open Graph applications. With the launch of Open Graph actions in September last year, Facebook has put into place what seems to be a major building block for the social network to realize its goal of being a platform that gives developers the power to transform a range of industries. It is likely to have been a key change Zuckerberg wanted to make before beginning the IPO process.

Facebook reached the 500-shareholder limit last year, which would have forced the company to release its financial statements even if it didn’t make a public offering. As Google did when faced with a similar situation, Facebook decided to file for an IPO anyway in February. Despite the “quiet period” that follows an IPO filing, the company hasn’t shown any signs of slowing progress. It introduced a number of features for marketers and advertisers, including mobile Sponsored Stories, Timeline for pages and offers. It announced the App Center and a beta program for paid apps. Facebook also bought photo sharing app Instagram for $1 billion, and acquired a few smaller mobile startups. This was all in addition to the dozens of tests and redesigned features Facebook implements on a weekly, if not daily, basis.

Now will be the real test of whether or not the company can maintain focus while being on the public market. A dual-class stock structure introduced in 2009 gives existing shareholders 10 times the voting power of new shareholder so the board has more power over the long-term direction of the company without feeling short-term pressures from investors. Zuckerberg himself controls about 56 percent of the voting power.

Images below from Mark Zuckerberg’s Timeline and the Nasdaq live feed. Image above from Facebook.