Basically there was a mysterious "official message" both on the US and EU servers from a bewildered hobbit, and several people doing their dailies in Enedwaith spotted a new black rock that starts a new deed. The deed is called Mysterious Relics and it requires you to find five relics scattered around Eriador.
I'm certain the newly appeared mysterious relics are representing the five gaunt-lords, "embodying death, pestilence, famine, war, and purest evil". There was a thread on the US forums some time ago, speculating their involvement in future content, but right now I can't find it - however certain quests in Enedwaith revealed the last, previously unnamed Gaunt-lord, so it's all becoming quite clear now. If anyone has a link to that thread I'd surely appreciate it, since I'd like to add the Gaunt-lords' names to this post but can't find them at the moment.
So here are my conclusions:
Thror's Coomb is most likely "purest evil", and it's probably linked both to the last Gaunt-lord (which appeared briefly in a quest instance nearby) and also the closed-off castle in the same region.
Oatbarton is "famine", and fits with the whole hobbit&food theme (and the blighted pipeweed farm here could be a nod to Saruman buying pipeweed from the Shire). Also check out this official message: A Strongly-Worded Letter from Bungo Grubb.
North Downs (William Peake's farm) is "war"; the farm where this relic appeared has been burned down. Probably also linked to the new town just around the corner.
Forochel is "death", the dialogue speaks of "mounting sense of fear".
Trollshaws (Laenan Caves) is "disease" and linked to the mysterious door, which apparently leads to an underground passage to an ancient temple where men of Rhudaur worshipped evil spirits.
Here's the tl;dr:
After completing the deed you get a nice title: Calm Before the Storm. Sadly, this deed gives no TP. But the excitement was surely worth it!
UPDATE: Many thanks to Anuhart for finding the right link; this thread from July reveals both the 'domains' of the Gaunt-lords as well as some very interesting bits from the original Volume 1 storyline. These are, as far as we know now, the five Gaunt-lords and their respective domains:
Drugoth the Death-monger, DEATH (Minion of Shadow)
Ferndur the Virulent, PESTILENCE (Minion of Plague)
Thadur the Ravager, FAMINE (Minion of Misery)
Ivar the Bloodhand, WAR (Minion of Battle)
Gortheron the Doom-caller, PUREST EVIL (his title is Minion of Plague as well, either it's a bug or he's a minion of Ferndur and we've yet to see the BBEG!)
This is what Gortheron tells the player during a quest instance in Enedwaith:
Gortheron the Doom-caller says, "How dare you disturb my work here! My brother was felled by the Free Peoples of this world, and I sought to return him to his proper place."
Gortheron the Doom-caller says, "Now he lies waiting and in rest. You seem to have undone some of my work here, but my forces shall lay waste to this place."
Gortheron the Doom-caller says, "Now I shall depart, but I will have vengeance for my fallen brethren. You shall rue to the day that you crossed paths with Gortheron the Doom-caller!"
So I guess it's fairly certain that the upcoming instance/raid cluster will be about the return of the Gaunt-lords, and I'd guess that the instances will be spread around Eriador near the places where these relics now appeared (the new town in ND, the temple in TS, the Ironspan in Forochel are all pretty good candidates for instance entrances). The locations also coincide very well with the regions we visited in Volume 3 Book 1, when we were gathering the Rangers for the Grey Company. Now that they're gone it seems all sorts of nasty things are returning.
Interesting times ahead!