Facebook founder Mark Zuckerberg says his site is growing by one million users a week in the US, according to an interview he did with MSNBC’s Today Show published this morning. The show’s host, Matt Lauer, adds that it’s growing by more than 5 million users a week worldwide. This is strikingly fast growth even compared to the company’s most recently published numbers.

But what about making money from all those users? Zuckerberg claims that a “few different lines” of revenue are growing “very quickly” and that he’s especially happy with how that effort is going in this economy.

But what about microblogging site Twitter, rival social network MySpace (which is still larger in the US) and other services? He says Facebook is differentiating itself through things like easy photo-sharing (it has more than a billion photos shared per month) and privacy controls so people can make sure those who are most special in their lives can see certain information others can’t. In a further illustration of that point, The Economist recently published an article quoting a Facebook “in-house sociologist” who said the average user spends most of their time communicating with only a handful of close friends.

Also of note: Zuckerberg admits that back when he started the site, in 2004, he didn’t foresee his company being one of the main ways that people share information on the web — just that there would be services to help people do so.

Lastly, I should point out that the interview also rehashes a bunch of recent news about the company’s changes to its terms of service. You can find our previous coverage of that subject first here, then here and most recently here).

Update: A quick look at AllFacebook’s demographic data about the site — drawn from Facebook’s advertiser reporting tools — corresponds to the US growth rate that Zuckerberg indicates (and in fact suggests it’s growing even faster).

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