Try this Try assigning time() to a variable then add that to the rename.
EG:
if ($_FILES['foto']['type'] == "image/jpeg" ||
$_FILES['foto']['type'] == "image/pjpeg"){
//nombre de la imagen
$timestamp = time();
//movemos la imagen.
move_uploaded_file($_FILES['foto']['tmp_name'],
"../fotografias/".$timestamp.".jpg");
HTH,
Karl DeSaulniers Design Drumm http://designdrumm.com
