This morning’s Observer column.

It was announced last week that the population of Facebook now exceeds that of America. Since mid-September the social networking service has added 50 million users, which means it now finds itself with 350 million of them. I am sure that Mark Zuckerberg, the founder of Facebook, takes the same view of his subscribers as PG Wodehouse attributed to the male codfish – “which, suddenly finding itself the parent of three million five hundred thousand little codfish, cheerfully resolves to love them all”. But even Zuckerberg must be wondering how he can monetise the little darlings.

There they are, cavorting in the corner of cyberspace so thoughtfully and expensively provided by him, where they post photographs of themselves in embarrassing situations, write affectionate or silly messages on one another's "walls", become "fans" of obscure comedians, join witty "groups" to support the Tiger Woods driving school and do other cool things too numerous to list. And all without paying a cent…

LATER: It’s interesting to see how this piece has been picked up across the Twitterverse — and slightly misinterpreted as a claim by me that Facebook won’t make money. I have no idea whether it will or not. All I was trying to say is that advertising isn’t necessarily the key to Facebook profitabiity. This is because the service is not primarily about content but activity. Maybe that can be monetised, but at the moment it’s not clear how.

What I was trying to say is that the hopes of content providers that they will make money from advertising may turn out to be fantasies. The only online business that really makes money from advertising is search. Which is why Google is as big as it is.