Is it me, or did the author tack on a new topic regarding the use of && and ||?

The fact that they return the controlling operand is quite useful. Consider a situation where you want to check the property of an object, but don't know if that object is null:

  var foo = obj && obj.bar;

I find this much more readable than:

  var foo = null;
  if (obj) {
    foo = obj.bar;
  }

You can accomplish the same thing with a ternary operator, but it's longer and, to my eyes, less scannable:

  var foo = obj ? obj.bar : null;

Also useful when setting optional parameters:

  function myFunc(foo, bar) {
    foo = foo || {};
    bar = bar || 'default_value';
  }

(take care however: the empty string evaluates to false, as does [] and 0)