With the DSi replacing it in nearly every respect aside from price and GBA compatibility, it was bound to happen eventually. According to a GameStop memo, Nintendo has retired the DS Lite in North America. Shipments have been called off, with remaining stock representing the last batch of retail units:
New DS Lite systems have been discontinued and stores will no longer be replenished on this product[...]
Continue reading: GameStop Memo Suggests DS Lite Is Discontinued...