Facebook's JS SDK doesn't support registering multiple 'ready' handlers. So here's an implementation inspired by Twitter's SDK. (uses underscore)
window.fb = (b = { _e: [], ready: function(f){ b._e.push(f); } });
window.fbAsyncInit = function() {
fb.ready = function(f){ f(); };
_.invoke(fb._e, 'call');
};
fb.ready(function(){ console.info("facebook sdk loaded"); });