[0] =>
      [date] => 2012-05-01
      [revenue] => 100
[1] =>
      [date] => 2012-05-02
      [revenue] => 200

[0] =>
      [x] => 2012-05-01
      [y] => 100
[1] =>
      [x] => 2012-05-02
      [y] => 200

$final_array = array();
$max = count($start_array);
for ($j = 0; $j < $max; $j++) {
  $final_array[] = array('x' => $start_array[$j]['dateid'], 'y' => $start_array[$j]['ctrl_version_revenue'] );
}

foreach( $start_array as &$arr ) {
  $arr["x"] = $arr['date'];
  unset( $arr['date'] );
  $arr['y'] = $arr['revenue'];
  unset( $arr['revenue'] );
}
unset($arr);

$new_arr = array_map(function ($val) {
  return array_combine(array('x', 'y'), $val);
}, $arr);

foreach ($arr as &$el) {
  $el = array_combine(array('x', 'y'), $el);
}

$new_keys = array( 'old1'=>'new1', 'old2'=>'new2', ... );
foreach( $array as $key=>$value ) $newarray[$new_keys[$key]]=$value;