How to create a streaming API with NodeJS
You would want to set up a system that keeps track of incoming requests and stores their response objects. Then when it's time to stream a new event from FriendFeed, iterate through their response objects and responses[i].write('something') out to them.
Check out LearnBoost's Socket.IO-Node, you may even just be able to use that project as your framework and not have to code it yourself.
From the Socket.IO-Node example app (for chat):
io.listen(server, { onClientConnect: function(client){ client.send(json({ buffer: buffer })); client.broadcast(json({ announcement: client.sessionId + ' connected' })); }, onClientDisconnect: function(client){ client.broadcast(json({ announcement: client.sessionId + ' disconnected' })); }, onClientMessage: function(message, client){ var msg = { message: [client.sessionId, message] }; buffer.push(msg); if (buffer.length > 15) buffer.shift(); client.broadcast(json(msg)); }});