(PECL memcached >= 0.1.0)
Memcached::getMulti — Retrieve multiple items
    Memcached::getMulti() is similar to
    Memcached::get(), but instead of a single key
   item, it retrieves multiple items the keys of which are specified in the
   keys array. If cas_tokens
   variable is provided, it is filled with the CAS token values for the found
   items.
   
Note:
Unlike Memcached::get() it is not possible to specify a read-through cache callback for Memcached::getMulti(), because the memcache protocol does not provide information on which keys were not found in the multi-key request.
   The flags parameter can be used to specify
   additional options for  Memcached::getMulti(). Currently,
   the only available option is
   Memcached::GET_PRESERVE_ORDER that ensures that the
   keys are returned in the same order as they were requested in.
  
keys
     Array of keys to retrieve.
cas_tokens
     The variable to store the CAS tokens for the found items.
flags
     The flags for the get operation.
   Returns the array of found items or FALSE on failure.
   Use  Memcached::getResultCode() if necessary.
  
Example #1 Memcached::getMulti() example
<?php
$m = new Memcached();
$m->addServer('localhost', 11211);
$items = array(
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => 'value3'
);
$m->setMulti($items);
$result = $m->getMulti(array('key1', 'key3', 'badkey'), $cas);
var_dump($result, $cas);
?>
The above example will output something similar to:
array(2) {
  ["key1"]=>
  string(6) "value1"
  ["key3"]=>
  string(6) "value3"
}
array(2) {
  ["key1"]=>
  float(2360)
  ["key3"]=>
  float(2362)
}
Example #2 Memcached::GET_PRESERVE_ORDER example
<?php
$m = new Memcached();
$m->addServer('localhost', 11211);
$data = array(
    'foo' => 'foo-data',
    'bar' => 'bar-data',
    'baz' => 'baz-data',
    'lol' => 'lol-data',
    'kek' => 'kek-data',
);
$m->setMulti($data, 3600);
$null = null;
$keys = array_keys($data);
$keys[] = 'zoo';
$got = $m->getMulti($keys, $null, Memcached::GET_PRESERVE_ORDER);
foreach ($got as $k => $v) {
    echo "$k $v\n";
}
?>
The above example will output something similar to:
foo foo-data bar bar-data baz baz-data lol lol-data kek kek-data zoo