Are +0 and -0 the same?

Question

Reading through the ECMAScript 5.1 specification, +0 and -0 are distinguished.

Why then does +0 === -0 evaluate to true<

Answer 1

Answering the original title Are +0 and -0 the same?:

brainslugs83 (in comments of answer by Spudley) pointed out an important case in which +0 and -0 in JS are not the same - implemented as function:

var sign = function(x) {
    return 1 / x === 1 / Math.abs(x);
}

This will, other than the standard Math.sign return the correct sign of +0 and -0.