After an official report, a block engraved with the Star of David has been removed from the Ptolemaic temple of the god Osiris Nesmeti on Elephantine Island in Aswan.This article is not the most lucid, but it seems to be implying that a hexagram carved on this Ptolemaic temple to Osiris may be ancient. That's possible, and the hexagram is known in Jewish iconography as far back as late antiquity, but that does not mean that this particular case is a Jewish symbol. I don't know of it being such as early as the Ptolemaic period and the architectural context in this case is not promising. Also, I don't know what part, if any, the hexagram symbol may have played in Hellenistic-era Egyptian religion. The stone is now being studied, so let's wait and hope for more information.
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I have mentioned Elephantine island many times in connection with the important Judean Aramaic papyri from the fifth century BCE which have been excavated there. Background here and here and links.
UPDATE (29 March): Reader Robert Schwartz e-mails:
I would like to supplement your essay titled above with:
The Messianic Idea in Judaism: And Other Essays on Jewish Spirituality by Gershom Scholem, Schocken, 1995
http://www.amazon.com/Messianic-Idea-Judaism-Essays-Spirituality/dp/0805210431/
There is a chapter "The Star of David: History of a Symbol" You can read part of it by using the "Look Inside" feature of the Amazon Web Site. Other Parts are on Google Books.
Scholem sees the hexagram connection with Judaism as quite recent, at least in the scale of Jewish history.