I'm going to remove promises entirely. For places where promises would
be used (fs, dns) I will instead use a standard callback interface:

  method(arg0, arg1, arg2, function (error, result0, result1) {
     puts('complete');
  });

That is, the completion callback will always be the last parameter and
the first argument the completion will always be reserved for an error
object. By following this scheme everywhere, I'm confident that very
good user-land deferred/promise/continuation libraries will spring up.

Expect this interface in the next version of node, 0.1.30.