I wasn't able to attend the ADS WOTY vote yesterday evening, but I understand it was a first-round landslide for because, beating out Slash, twerk, Obamacare, and selfie. According to the ADS announcement,
“This past year, the very old word because exploded with new grammatical possibilities in informal online use,” [Ben] Zimmer said. “No longer does because have to be followed by of or a full clause. Now one often sees tersely worded rationales like ‘because science’ or ‘because reasons.’ You might not go to a party ‘because tired.’ As one supporter put it, because should be Word of the Year ‘because useful!’”
You can hear Ben Zimmer discussing the run-up to the vote a couple of days ago on NPR's Morning Edition ("American Dialect Society To Vote On Word Of The Year", 12/31/2013), and no doubt we'll have additional coverage later, but meanwhile there's some discussion from last summer in "Because NOUN", 7/12/2013.
Geoff Pullum's comment: "I'm pleased to see a preposition win an award like this for once; nouns have had it far too easy."
Update — The cases with adjectives strike me as less innovative than the because NOUN examples are. Some relevant traditional (conjunction-like) examples:
A thousand vague fancies oppressed and disconcerted me-fancies the more distressing because vague.
Lacking that safe spot, conversations with Clarence could be scary, because unscripted.
Not showy and glittery like the peeling palaces along the Grand Canal, once glamorous beauties now slipping into their dotage, this campo was authentic Venice, surviving because unvisited.
He is called a "black sheep, and his "shabby frock-coat" supplies us with the word frock, which Skeat derives from "Flock:" "Probably so called because woollen ."
A thousand vague fancies oppressed and disconcerted me — fancies the more distressing because vague.
From 1820: This would at least be honest, though I think it would be unwise, because unnecessary.
From 1834: Still does he sometimes introduce into his speeches bursts of eloquence, which stir the heart like the voice of a trumpet, and are the more stirring because unexpected.
From 1840: The storm of war has rolled off to distant borders; or if, indeed, it be lowering near again, its terrors are unfelt, because unseen .
Update #2 — Commentary by Stan Carey, "‘Because’ is the 2013 Word of the Year, because woo! Such win"; by Arika Okrent, "The American Dialect Society’s Word of the Year is 'Because'"; Gretchen McCulloch, "Why the new 'because' isn’t a preposition (but is actually cooler)".