I can't speak with total authority, but I authored the library so I may have some insight. I'm not aware of anyone using Javelin for any serious development outside of Facebook, although there are a few hobbyists playing around with it. read more
I'm not aware of anyone using Javelin for any serious development outside of Facebook, although there are a few hobbyists playing around with it. Update: As of April 2011, the Phabricator open source project uses Javelin, and is sort of outside-of-facebook. read more
First of all, their core services are based on Thrift which Facebook has made opensource; also, they have their own library based on JavaScript. They are probably incorporating a lot of standard DOM scripting (but obfuscated) code in and above the user-space. read more