When Facebook made its stock exchange debut on Friday it marked a cultural, technological and even social milestone: a dazzling media event that said more about this particular moment in human connectivity than it did about the long-term value of the company itself.
The feverish investor interest that pushed the social network's valuation sky high on its launch was thoroughly predictable, the tip of a steep growth line that extends from zero to more than $100bn (£63bn) across just eight years. In that time, the explosion in personal, portable internet access, fuelled by the rise of smartphones and consumers' appetite for social sharing, created the perfect conditions for the Facebook phenomenon.
But sceptics continue to question Facebook's revenue prospects. It seems advertisers aren't necessarily as convinced about its value as its new investors.
Just days ahead of the IPO one of the world's biggest advertisers, General Motors, said it was withdrawing its advertising from the social network because it was simply not convinced it worked. Although GM is continuing to invest $30 million in creating content for Facebook, such as brand pages, which are free to upload, it is culling the $10m it actually pays Facebook for ad space.
For a company that has been so dazzling in so many ways, commercially Facebook has looked leaden. Part of the problem is that it hasn't always made it easy for brands to track and evaluate exposure to their ads. At the same time its advertising model has been reshaped too often, as the site struggles to find a formula that successfully leverages the commercial value of its massive user-base. Last year Facebook made less than $4 in ad revenue from each of its active users.
That, analysts say, has to change. After Friday's IPO they calculate that if the company is to justify the market's valuation, its ad revenues must grow by more than 40 per cent a year.
The real challenge will be to do that without alienating its 900 million consumers, many of who – IPO or not – feel that Facebook really belongs to them.
Claire Beale is editor of Campaign