Mark Zuckerberg and Paul Graham get ready to speak at Facebook Developer Garage - Startup Edition.

Today I visited the Facebook headquarters for a mini developer conference for Y Combinator companies. The turnout was huge for what I'd expect for this kind of event -- probably around 150 YC folks. It began with talks by Mark Zuckerberg, Brett Taylor (founder of FriendFeed, which was acquired by Facebook about a year ago, and now Facebook's CTO), and Paul Graham.

Zuckerberg talked a bit about the history of Facebook, and how our innate interest in humans makes social apps much more compelling than non-social apps. He said Facebook sees itself as primarily managing peoples' social graphs and allowing third-party services to build off it to create new services that Facebook wouldn't have thought of.

He also made the observation that games seem to be the first indicator of a good platform. Games were among the first applications to become popular when personal computers first became available, as well as on the iPhone and on Facebook when they started allowing thrid-party apps.

Brett discussed their public APIs, and also talked about how they allow some sites (such as Yelp) to access APIs not yet available to the public. He said they would be making new APIs available to Y Combinator companies before they released the to everyone, and offer all the support they're able to for companies who want to use them. One option he proposed is for companies to come work at the Facebook office for a few days next to the API team so they could get help and give input during development.

Paul Graham's discussed the advantages startups have over established companies -- mainly that there are lots them that are all willing to take bigger risks than companies that have to worry about things like maintaining revenue. Most startups will fail, but the few that succeed will have produced something their bigger competitors couldn't have.

After the talks, the three of them had a Q&A session. The most interesting response was from Zuckerberg to a question about privacy. He gave a history of Facebook's privacy settings, saying that when Facebook first began, it was a more private way for people to share photos and notes on the web than had previously existed since it would only be accessible to users' friends. As peoples' friends lists began to expand from only close friends to include acquaintances, privacy became an issue -- if people had content they didn't want everyone to see, some of the people they wanted to keep it private from were likely on their friends list. This prompted the creation of privacy controls that allowed users to specify which of their friends were allowed to see what content. As the types of content available on Facebook increased with the addition of apps and more features, so did the number of privacy options. Eventually there were so many that managing them all was impractical. He said their current (and future) strategy is creating groups of options that can be set together to make them more manageable.

The Q&A was followed by a barbecue on their lawn. At one point I found myself chatting in a group with Zuckerberg. Someone asked him if he was planning to see the Facebook movie. He said he wasn't sure -- he was there when Facebook was created and it wasn't all that exciting; mostly a lot of coding and Red Bull.

He also said that he makes it a personal policy not to read press about Facebook -- something like, "Sometimes the press will be saying great things about you while you know you're making mistakes, and other times they'll be saying bad things when you aren't really doing anything differently. It just goes in cycles. We have to trust our internal compass for what we should be doing, and make sure to always listen to our users."

On the way out I got a glimpse of their workspace. They have an open floor plan, with rows of desks facing each other -- no cubicles or offices. While I waiting for the shuttle home, I chatted with a Facebook programmer who talked about how much he likes the open floor plan. He said it made it really easy to talk to people since he could just walk over to their desk. (It sounds like Facebook's avoided the problem Steve Blank talks about in The Curse of a New Building. He was a new hire, and had just completed their six-week bootcamp, which gets engineers up to speed on the code base and company practices. You can read more about Bootcamp here.

Facebook's front door with the letters H A C K.