Well, we're assuming it's a series, there has never been just one of these.
Marvel Comics released their second teaser for Monday (here's the first ), but this new one shifting gears to their familiar Marvel NOW!/All-New Marvel NOW! one-word teaser style. This one say "Resurrection" in a title or story arc of some kind by Brian Wood and Kris Anka.
Wood of course is the current writer of X-Men and Anka has worked on X-titles before like Uncanny X-Force and Wolverine and the X-Men and there is certainly any number of X-characters that could be 'resurrected'.
Whatever it is it drops in February and with February solicitations due in a week or two, readers won't have to wait long to find out what it is.