As MMO Champion reports, the MoP NDA will be lifted very soon. This is just a friendly reminder that expansions are a time of great change and that WoW Best In Slot will be adapting to whatever MoP throws at the item and gear scene. Traditionally changes to the core game have been implemented here relatively soon after they're made. Luckily Blizzard almost always gives us a window of time before an expansion where the expansion's mechanics are active and anything new can be anticipated.
As for actual expansion items, it's anyone's guess when those will begin to be revealed. For most this won't matter until a little while after the expansion is up and running and people begin to look at optimizing their characters.