Skyrim - Snow Elves and Vampires in the first DLC?

Every site I visited this morning is linking to this Bethsoft forum post where a player has scanned the v1.5.26 Skyrim update file for the string "DLC01", concluding snow elves, vampires and crossbows will somehow combine for the first DLC. It's all speculation but seems based on reasonable evidence - with some information expected next week, we might not have long to wait.