A shard of pottery unearthed in a decade-old dig in southern Israel carried an inscription in early Semitic style spelling "Alwat and "Wlt", likely Philistine renderings of the name Goliath...
[Aren] Maeir, head of the archaeology department at Bar-Ilan University near Tel Aviv, told Reuters his excavators found the shard, possibly part of a bowl, about two metres underground at Tell es-Shafi.The dig is described here.
The mound where the dig took place is widely believed to be the site of the ancient city of Gath, which the Bible calls Goliath's hometown.
The Jersalem Post has a photo of the shard.
Looks authentic to me.