In one of the year's more interesting API announcements, the hugely successful social networking site Facebook launched their own API this week. Up to this point most social networking sites including MySpace have been notoriously walled gardens (back in February I reported on a home-grown Facebook API). For a high-level overview of this one, TechCrunch gives a good summary here. As for the API itself: it uses a REST-based protocol and is available for commercial and non-commercial use up 100,000 calls within a 24-hour window. There is now a Facebook API entry in the database here. As well as Facebook Friend Mapper, the first Facebook mashup. A map of course. Will it popular? You bet. Within 48 hours there were already 79 discussion topics kicked-off on their discussion board, a pending site www.facebookapplications.com, projects at Google Code, and IRC discussions on it in places like the "#facebook" chat room on freenode. BTW, there's been some discussion lately about the responsibilities of companies that rely heavily on open source in terms of "giving-back" to the community. See Tim O'Reilly's notes on Open Source: Architecture or Goodwill? and some of the links from there for examples. It seems that Facebook is diving right-in on this one and if you check this page you'll see they've contributed back to the phpshell and memcached open source projects.