There was a fascinating article a couple days ago in the International Herald Tribune, about a text, potentially associated with the Dead Sea Scrolls, that has been termed "Gabriel's Revelation"; Time also has an interesting (and surprisingly reasonable) take on it. "Gabriel's Revelation" is apparently a stone on which are written a series of some 87 lines in Hebrew, believed to date to the first century BC. One of the various interesting things about this text is that it may refer to an otherwise unattested Jewish belief in a suffering Messiah who would die and then rise again in three days. A "best guess" at the text (in Hebrew) can be found on page 4 of the PDF here.
This would be a pretty interesting artifact if (a) the text is authenticated (apparently its provenance is somewhat obscure), and (b) the reading which supports the claim receives more widespread support. But there's the catch: apparently the text is exceedingly hard to read at exactly this point.
The slaying of Simon, or any case of the suffering messiah, is seen as a necessary step toward national salvation, [Knohl] says, pointing to lines 19 through 21 of the tablet - "In three days you will know that evil will be defeated by justice" - and other lines that speak of blood and slaughter as pathways to justice.
To make his case about the importance of the stone, Knohl focuses especially on line 80, which begins clearly with the words "L'shloshet yamin," meaning "in three days." The next word of the line was deemed partially illegible by Yardeni and Elitzur, but Knohl, who is an expert on the language of the Bible and Talmud, says the word is "hayeh," or "live" in the imperative. It has an unusual spelling, but it is one in keeping with the era.
Two more hard-to-read words come later, and Knohl said he believed that he had deciphered them as well, so that the line reads, "In three days you shall live, I, Gabriel, command you."
In other words, to put it generously, the assertion that the text refers to a belief in a Messiah who will suffer and rise after three days is unproven at this point. That it might refer to such a belief is about as close as we can come.
I should add that at least one assertion made by Knohl certainly isn't true, or at least, doesn't have the shattering implications that he claims:
"This should shake our basic view of Christianity," he said as he sat in his office of the Shalom Hartman Institute in Jerusalem, where he is a senior fellow and the Yehezkel Kaufman professor of biblical studies at Hebrew University. "Resurrection after three days becomes a motif developed before Jesus, which runs contrary to nearly all scholarship. What happens in the New Testament was adopted by Jesus and his followers based on an earlier messiah story."
This would "shake our basic view of Christianity" only if we're scholars with very specific axes to grind about the nature of first century Messianic expectations. (That particular set contains a very few, highly inbred members, for what it's worth.) If we're just regular Christians, I can't think of any way that this stone would have a substantial impact on us at all, other than as an interesting artifact. Jesus himself held to the belief that the Messiah would die and be raised after three days, and in a famous passage (Luke 24:25-27) showed to his supporters in some detail how this belief was supported by the Old Testament. Many Christians have also believed that the story of the Messiah was prefigured in such diverse pagan sources as the myth of Osiris, or even the Eclogues of Virgil:
Now is come the last age of the Cumaean prophecy: the great cycle of periods is born anew. Now returns the Virgin, returns the reign of Saturn: now from high heaven a new generation comes down. Yet do thou at that boy's birth, in whom the iron race shall begin to cease, and the golden to arise over all the world, holy Lucina, be gracious; now thine own Apollo reigns. And in thy consulate, in thine, O Pollio, shall this glorious age enter, and the great months begin their march: under thy rule what traces of our guilt yet remain, vanishing shall free earth for ever from alarm. He shall grow in the life of gods, and shall see gods and heroes mingled, and himself be seen by them, and shall rule the world that his fathers' virtues have set at peace.
Or Plato's Republic:
And at his side let us place the just man in his nobleness and simplicity, wishing, as Aeschylus says, to be and not to seem good. There must be no seeming, for if he seem to be just he will be honoured and rewarded, and then we shall not know whether he is just for the sake of justice or for the sake of honours and rewards; therefore, let him be clothed in justice only, and have no other covering; and he must be imagined in a state of life the opposite of the former. Let him be the best of men, and let him be thought the worst; then he will have been put to the proof; and we shall see whether he will be affected by the fear of infamy and its consequences. And let him continue thus to the hour of death; being just and seeming to be unjust. . . The just man who is thought unjust will be scourged, racked, bound --will have his eyes burnt out; and, at last, after suffering every kind of evil, he will be impaled.
In other words, once the scholars arrive at a consensus (a process that might take decades), Gabriel's Revelation will probably shed some light on otherwise obscure elements of first century Judaism, and maybe even hint at Jewish sources for certain Christian beliefs. But it's hardly a challenge to Christianity that one particular aspect of the Christian story might have been accidentally hit upon, guessed at, understood, or even revealed, prior to the advent of Christ Himself.