I just got back from the Facebook Developer Garage in Seattle. These are local events started by a local sponsor for people interested in Facebook apps. There were a handful of people from Facebook including the Senior Platform Manager who spoke.

Overall, a really interesting event. Some of my impressions:

• Facebook is an incredible phenomenon – 33 million users, adding 100,000+ every day.
• The platform is real – 2000 apps in 2 months. 75% of active users have at least one app installed
• The talk is “open platform” but Facebook is in charge. They throttle things like invites and the number of notifications apps can put in the mini-feed (1 per user per day.) Like any other application built on a free api – you have no rights. You get what you pay for.
• Lots of Ruby developers in attendance. Probably the single largest group which is sort of crazy in Microsoft country.
• Virtual currency and Ad Networks are interesting right now. However, money is changing hands across Facebook apps. They’re encouraging more app developers to seek to get outside ad dollars into Facebook.
• Top app is seeing $20 CPM; $5-10 is more reasonable.
• Engagement is the key metric. Pageviews/user, repeat visits, time on site. People are more focused on raw numbers right now.

I think the talk about engagement is critical. Anyone will try your app once. The key is how often they come back and actually use your product. This is something we’re very focused on at Judy’s Book. Unless people are choosing to opt in to the experience you’re creating after their initial trial, you’re nowhere.