Not that we really need much more confirmation, but the small-type in the new Moto E promo video mentions Android 4.4.3 KitKat — which, as we know, doesn't quite officially exist yet. Unofficially, of course, it's there. And it's coming. Start at 38 seconds to see it.
For what it's worth, the Moto E units on hand at today's London event were all running Android 4.4.2.