Сергей

var isFormFocused = false;
$('#callback-form :input').focus(function() {
  if(!isFormFocused) {
    isFormFocused = true;
  };

  if(isFormFocused){
    $('#sidebar').animate({width: '100%',left: '0%'}, 200);
  };
});

$('#callback-form :input').blur(function() {
  // задержка все-таки необходима
  setTimeout(function () {
    if(0 === $('#callback-form :focus').length) {
      isFormFocused = false;
    };
    if(!isFormFocused){
      $('#sidebar').animate({width: '50%',left: '50%'}, 200);
    };
  }, 100);
});