Hola, tengo duda en esta linea:
Código PHP:
if (move_uploaded_file($_FILES['upload']['tmp_name'], "uploads/{$_FILES['upload']['name']}")) //para que son las llaves?
//Yo lo pondria asi:
if (move_uploaded_file($_FILES['upload']['tmp_name'], "uploads/".$_FILES['upload']['name']."")
Saludos.