OK, from reading the code it looks like the livedata endpoint gets plugged in at load time (https://github.com/meteor/meteor/blob/release/0.6.6.3/packages/livedata/stream_server.js#L58), but webapp doesn't start listening until after all the startup callbacks have run (https://github.com/meteor/meteor/blob/release/0.6.6.3/packages/webapp/webapp_server.js#L428).

So the pattern of using `withAutoUpdateVersion` with a callback should be unnecessary here also.