Promises are likely to be baked into JavaScript at some point in the future[1], so I would recommend becoming familiar with them now. Even if you don't use the pattern personally you will likely run into libraries that do use it once it is part of the spec.
I don't too much like the promise pattern this article gives, Q is the definitive implementation: http://documentup.com/kriskowal/q/
[1]http://wiki.ecmascript.org/doku.php?id=strawman:concurrency