Given the different versions of L&M which will be happening on different shards, I'm not sure that it's part of the story arc at all, but rather a chance to let the EMs show their stuff by running an actual event.
An example: Kas will be likely running a quest to find him on Catskills, while on Chesapeake, they're holding a day long festival run by both players and the EM. I see little common ground to further the inter-shard story. Then again, the stories could just be required to end at the same place and what happens in between is completely up to the EM.
Anyhow, the quests from last weekend on other shards are likely not directly connected to L&M. Or at least no more connected than what happened when Kas vanished.
Makes it interesting, when I can't use spies...er... contacts on other shards to tell what will likely happen on Catskils.