Facebook mobile ad revenues are now at a $300 million run rate.

5:12 PM | Sheryl Sandberg is taking the phone

Ad revenue grew 41%.

23% of ad revenue came from mobile, up from 14% in Q3.

Focus in Q4 was to scale products launched in 2012.

5:14 PM | Facebook's three priorites

Building products and tools that create value for all marketers. Brand, Direct, Local, Developers

Proving that value.

Taking advantage of mobile.

...

5:33 PM | Analyst wants to know: How'd the mobile run rate go from $270mm to $300mm+? How are you improving ad quality?

Ebersman: We think mobile can be huge. If you compare overall revenue, it doubled. We're still really early.

Zuckerberg talks about ad quality. He says Facebook improved its News Feed algorithm and that likes and comments increased by 50%. Meanwhile, ads brought likes and comments down by 2%. So net, engagement is up, even w/ ads.

...

5:50 PM | Analyst wants to know about how Facebook is measuring ad performance for marketers Sandberg is talking about how the click is worthless. 99% of people who buy a product advertised on Facebook didn't click on the ad.

Conversion measurements only launched in mid-December. Could do a lot more, she says. She says it'll be exciting to do it on mobile. We can now measure all the way from seeing an ad on a mobile device to purchasing the product in a store. 

5:51 PM | Catch that? Impressive!

Facebook can tell if you saw a mobile ad and then bought the product advertised.

5:54 PM | Analyst wants to know about engagement. Are post-college people engaging more, or leveling off? What are the near-term oppty in social ads?

Ebersman talks about engagement. We don't break out engagement by age. The overall marketplace is expanding in terms of the amount of time people are spending connected and sharing with friends. That's good for Facebook because we're a leader in the market. 

Sandberg talks about the opportunities. Mobile gets 1% of ad revenue and 10% of time consumed. Other low-hanging fruit: Ramp with large advertisers, help them measure, help them use custom targeting instead of broad ad buys.

"Facebook is a mobile company," declared Mark Zuckerberg today.

I believe him.

Other stats as of January 2013:

1. Facebook has 618 million daily active users.

2. Facebook stores more than 240 billion photos, with some 350 million new photos uploaded a day. Read more.

3. Wall Street was looking for year-year revenue growth greater than 32% (it was 40%) and operating margins greater than 12.13% (it was). Read more.