Answer to the stackoverflow question http://stackoverflow.com/questions/3678457/how-to-array-merge-a-dynamic-array-based-on-one-of-its-value-similarity/5049383#5049383

gistfile1.php

<?php
$_Retreived = array(
  "website1.com" => array(
    array('60" BRAVIA LX900 Series 3D HDTV', 'website1.com', 5299.99),
    array('52" BRAVIA LX900 Series 3D HDTV', 'website1.com', 4499.99),
    array('46" BRAVIA LX900 Series 3D HDTV', 'website1.com', 3699.99),
    array('40" BRAVIA LX900 Series 3D HDTV', 'website1.com', 2999.99)
  ),
  "website2.com" => array(
    array('Sony 3D 60" LX900 HDTV BRAVIA', 'website2.com', 5400.99),
    array('Sony 3D 52" LX900 HDTV BRAVIA', 'website2.com', 4699.99),
    array('Sony 3D 46" LX900 HDTV BRAVIA', 'website2.com', 3899.99),
  ),
  "website3.com" => array(
    array('Sony 40" BRAVIA LX900 3D HDTV', 'website3.com', 999.00)
  ),
  "website4.com" => array(
    array('60" BRAVIA LX900 Series 3D HDTV', 'website4.com', 888.00)
  ),
  "website5.com" => array(
    array('32" BRAVIA LX900 Series 3D HDTV', 'website4.com', 888.00)
  ),
);

$Product_Info = find_products($_Retreived);
$Prices = array_values($Product_Info);

print_r($Prices);
// print_r($Product_Info);

function find_products($_Retreived) {
  $Product_Info = array();

  foreach($_Retreived as $site1 => $products1) {
    foreach(array_reverse($_Retreived, true) as $site2 => $products2) {
      if ($site1 !== $site2) {
        foreach ($products1 as $index1 => $product1) {
          list($name1, $site1, $price1) = $product1;

          foreach ($products2 as $index2 => $product2) {
            list($name2, $site2, $price2) = $product2;

            if ($common_name = get_common_name($name1, $name2)) {
              if (strstr($common_name, '"')) {
                $Product_Info[$common_name]['Name'] = $name1;
                $Product_Info[$common_name][$site1] = $price1;
                $Product_Info[$common_name][$site2] = $price2;
                // remove the matched products
                unset($_Retreived[$site1][$index1], $_Retreived[$site2][$index2]);
              }
            }
          }
        }
      }
    }
  }
  foreach($_Retreived as $site => $products) {
    foreach($products as $data) {
      if (!isset($Product_Info[$data[0]])) {
        $Product_Info[$data[0]] = array(
          'Name' => $data[0],
          $data[1] => $data[2],
        );
      }
    }
  }
  return $Product_Info;
}

function get_common_name($name1, $name2) {
  // replace non-word and non-whitespace chars, then split on whitespace
  $parts1 = preg_split('/\s+/', $name1);
  $parts2 = preg_split('/\s+/', $name2);

  // find the common words
  $intersect = array_intersect($parts1, $parts2);
  sort($intersect);
  // remove stop words
  return !empty($intersect) ? trim(preg_replace('/\s*Series\s*/', ' ', implode(' ', $intersect))) : false;
}

/*


Array
(
    [0] => Array
        (
            [Name] => 60" BRAVIA LX900 Series 3D HDTV
            [website1.com] => 5299.99
            [website4.com] => 888
            [website2.com] => 5400.99
        )

    [1] => Array
        (
            [Name] => 40" BRAVIA LX900 Series 3D HDTV
            [website1.com] => 2999.99
            [website3.com] => 999
        )

    [2] => Array
        (
            [Name] => 52" BRAVIA LX900 Series 3D HDTV
            [website1.com] => 4499.99
            [website2.com] => 4699.99
        )

    [3] => Array
        (
            [Name] => 46" BRAVIA LX900 Series 3D HDTV
            [website1.com] => 3699.99
            [website2.com] => 3899.99
        )

    [4] => Array
        (
            [Name] => 32" BRAVIA LX900 Series 3D HDTV
            [website4.com] => 888
        )

)

*/