He clearly states they don't care about profit: "At this point in the company’s evolution, I don’t see a huge need for the company to be throwing off a huge amount of profit. What’s the point? [...] If you prematurely optimize, you might get a bigger piece of a smaller thing."
On the other hand, they already have 400 million users, which is about 20% of the entire internet population in the whole world[1]. Part of me is thinking what exactly are they waiting for? Something tells me even if they were at 100% internet population, they would still be making meager profits and have an underwhelming IPO. But then again I'm a glass half empty kind of guy when it comes to Facebook.
No matter. It is still a good number to play with on their P&L statement. All they need to do is soundly (or incrementally) adjust their outgoing numbers then the profit will definitely increase.