Background here and links.
UPDATE: The New York Times has just published an article on the recent developments: Fresh Doubts Raised About Papyrus Scrap Known as ‘Gospel of Jesus’ Wife’ (Laurie Goodstein). There is new information in it, including further responses from Malcolm Choat, Roger Bagnall, and Karen King.
“This is substantive, it’s worth taking seriously, and it may point in the direction of forgery,” Karen L. King, the historian at Harvard Divinity School, said in a telephone interview, her first since the recent developments. “This is one option that should receive serious consideration, but I don’t think it’s a done deal.”I don't think the people arguing it's a fake "wanted it to be a fake." I was originally suspicious because it sounded too good to be true, and subsequent evidence has continued to point considerably more in the direction of a forgery than not. In any case, ad hominem criticisms can go in both directions and are ultimately unhelpful. The evidence remains to be evaluated on its own terms after all the accusations are done. The Lycopolitan John manuscript (the Qau Codex) was buried in a tomb, so it's hard to see how the Harvard John fragment could have been copied from it. I suppose it's possible that the Lycopolitan John manuscript had been copied (exactly according to its lineation) and the Harvard John fragment was copied centuries later (uniquely for a manuscript in the Lycopolitan dialect and, again, exactly following the lineation, this time of alternate lines) from this lost intermediate manuscript. Neither this nor any other scenario I can think of sounds likely to me.
Malcolm Choat, a Coptic expert at Macquarie University in Australia who cautiously contradicted the doubters in his paper last month for the Harvard journal, said in an interview that the new evidence was “persuasive,” but “we’re not completely there yet” — until the John and Jesus wife papyruses can be studied in person or using high-resolution images to understand their relationship. Roger Bagnall, a renowned papyrologist who directs the Institute for the Study of the Ancient World at New York University, and who early on deemed the Jesus’ Wife papyrus likely to be genuine, said in an interview about the skeptics, “Most of the people taking this view wanted it to be a fake, and they haven’t asked critical questions about their own hypothesis.”
Perhaps the copying of these two John texts was done in ancient times, not the modern era. Perhaps the John and Jesus’ Wife fragments were not written by the same hand: Indeed, the testing found that the ink is similar but not the same.
The critics have asserted it would not be hard for a forger to mix a batch of carbon-based ink that could fool scientists.
But Dr. Bagnall said, “I don’t know of a single verifiable case of somebody producing a papyrus text that purports to be an ancient text that isn’t. There’s always the first.”
The spotlight now turns to the provenance and the owner of the Gospel of Jesus’ Wife. Dr. King promised him she would not identify him publicly, but said she knows she is now under pressure to do so.
I don't know of any verified modern forgeries using papyrus, but there has been at least one modern (1960s) forgery using parchment: the notorious Hebron "Philistine" scrolls. It was a bad forgery, but it managed to fool a number of scholars. Producing a papyrus forgery is not greatly different in principle, although this one, if that is what it is, is more sophisticated in that it uses ancient materials. But we would expect the arms race between scholars and forgers to result in more sophisticated forgeries.
The most substantive point in Prof. Bagnall's reply is that the two documents may not be in the same scribal hand. That would weaken the connection between them. Some experts in Coptic paleography need to have a look at this question and give us evaluations of whether the two hands are the same.
UPDATE (6 May): For examples of papyrus forgeries, see here.