Today at the American Museum of Natural History, Facebook hosted its first conference for 1000 New York marketing types. It’s like an f8 that Madison Avenue cares about, but more than that, it’s also the F8 investors should care about.

Facebook depends on the people in this room more than anyone to remain as wildly profitable as it has been up until this point. Once Facebook is a public company, the pressure to post continually growing quarterly earnings, justifying the company’s lofty valuation, will be high. And those earnings will be tied entirely to the spending decisions of Madison Avenue.

If recent reports are true, such earnings may not be as obvious of a slam dunk as it seems. Last week VentureBeat reported that the company was on track to miss ad revenue expectations for the first quarter.

The string of new ad formats and Timeline for brands, announced in tandem with this event, is part of the company’s crucial drive to lure in more ad dollars. It’s interesting to me that right now, Facebook’s main product for advertisers is more beneficial for the long tail and not necessarily the biggest brand advertisers.

Those companies with the biggest presence on Facebook likely will spend more money on SaaS tools from the likes of Buddy Media to manage their page through owned media, not paid. Facebook’s own display ads aren’t much to get excited about.

Clickthrough rates are even lower than the rest of the Web’s, though new products like Sponsored Stories are an improvement. More importantly, they’re lower than that of other social networks like Twitter. Even if Facebook as a company and platform is far bigger and more mature than Twitter, it’s still competing with Twitter for ad dollars, or “share of wallet” on Madison Avenue.

If advertisers choose to allocate a certain amount of money to social, the breakdown between Facebook ads, Facebook owned content (brand pages, etc), Twitter and other emerging social networks (Foursquare?) means Facebook will need to fight other networks for each dollar.

Facebook COO Sheryl Sandberg charmed the crowd with a high level talk focused on “the shift from the wisdom of crowds to the wisdom of friends.” (A dig at the freewheeling open info flow of Twitter, Yelp or Google?) She was clearly trying to appeal to a more mature audience than Mark Zuckerberg would at the F8 developers conference. Sandberg noted that her young Facebook coworkers often ask her to look at new products because “they need to know what an old person thinks of it.”

Throughout the day Facebook will trot out David Fischer, Carolyn Everson and other “adults” they’ve brought in over the last year or so to court advertisers. Smart move. I don’t see a single Adidas sandal-clad Wannaberg (or Zucker-be?) in the house.