Several bloggers, including myself, have urged folks not to get too excited at this early stage about rumors regarding a very early – indeed, first-century – fragment of the Gospel of Mark having been found.
But it is important that one respond with calm patience, not with the assumption that the claim is bogus.
To illustrate the danger, I link to Timo Paananen’s post about Solomon Zeitlin’s insistence over the course of many years that the Dead Sea Scrolls were fakes or at best medieval manuscripts of little value or interest.
The best course is neither to assume authenticity and risk seeming to have been duped, nor to assume inauthenticity and risk finding ourselves insisting something is inauthentic even once test results are in and point towards authenticity. Patient temporary agnosticism seems far better than the other two options I just mentioned.