$facebook->api('/'.$uid.'/checkins', 'POST', array(
'access_token' => $facebook->getAccessToken(),
'place' => 'place_id',
'message' =>'I went to placename today',
'picture' => 'http://www.place.com/logo.jpg',
'coordinates' => json_encode(array(
   'latitude'  => 'lattiude',
   'longitude' => 'lattitude',
   'tags' => $uid),
 )
)