Several news outlets are reporting that biblical scholars Craig Evans and Daniel Wallace are working with a team that may have uncovered the earliest known copy of the Gospel of Mark. You can see full articles with all the details here and here.
In short, this fragment of the Gospel of Mark has been found in a paper mache mummy mask from Egypt, alongside several other documents that span the gamut from religious to business texts. Some of the business texts include dates which allow us to know that the mask was created sometime around 90 AD. For the Gospel of Mark fragment to have been included in 90 AD therefore requires it to be somewhat older than this. Prior to this, the earliest extant copies of Mark date to the 2nd century.
While it might seem surprising that a fragment of the Gospel of Mark should have been used for such a purpose, the practice was not uncommon among pagans who would not have regarded the text as valuable and were more interested in the paper it was written on. However, the fact that Egyptians were in possession of a portion of the Gospel of Mark around 90 AD suggests that Mark was already widely distributed by this date. This, in turn, provides additional weight to the conservative argument that Mark was written early, contrary to popular claims that Mark (and the rest of the Gospels) were written many decades after the events they record.