At the risk of hijacking the comment thread for an article about NodeJS to grandstand about CoffeeScript:

I'm not a big fan of leaky abstractions, and right now that's what CoffeeScript is. It will be somewhat less leaky once this has been resolved:

https://bugzilla.mozilla.org/show_bug.cgi?id=618650

…for all browsers.

I'm happy for CoffeeScript to exist, to be able to play with it, and to see its syntax inform the work on JS.next. It has a way to go before I'd be happy to use it in a production environment.