This will be my last post direct from the Future of Web Apps as day two draws to a close.

Dave Morin, Senior Platform Manager at Facebook, talked this morning about the site’s remarkable growth and its value as a developer platform. He says its user count is growing at 3% per week, which equates to doubling each 6 months or so. Even more impressive are its activity stats – 50 page views per user per day, according to Morin, with 50% of users logging in at least daily.

So what is the Facebook platform? Morin calls it “A standards-based advanced web service which enables you to access the social graph”, where “social graph” means the connections between people. If you build an application on this platform, you can hook into these connections. An attraction for developers is that applications can achieve rapid adoption through the viral networking that Facebook encourages.

For me, his talk was more notable for what it did not say, than for what it did. Morin referred to the oft-repeated Facebook problem, that developers fear their best ideas will simply get built into Facebook itself, but did not offer any comfort beyond bland reassurance. I’m also interested in the implications of Facebook becoming increasingly important as an identity provider. How does it compare to others such as Google, Microsoft, Yahoo, when measured against the laws of identity developed by Microsoft’s identity architect Kim Cameron, for example?

Joe Walker spoke on Comet, an API for two-way communication with the web browser. Fascinating session, if only for his description of the hacks required to make it work – web browsers are not designed for this. Interesting comment on IE and how it handles data in iFrames – “it’s not wrong, but all the other browsers do it better.”

Tom Coates from Yahoo spoke on FireEagle, the code name for a project which exposes an API for applications that provide location-based services. If you sign up, it uses a variety of techniques to detect your location. An application could then do things like advising the speed limit in your area, or giving you a weather forecast, or informing you of friends nearby, or any number of other possibilities. Intriguing stuff, but with security and privacy implications that have not been fully worked out. It will be interesting to track what happens once people begin to sign up, which will be possible shortly in the form of an early test release.