Not Double XP proper, which is confusing
Fresh off the Call of Duty: Uprising DLC release, Treyarch has announced a Double Weapon XP weekend for Black Ops II, which starts at 10AM PDT today (right around the time of this writing). Since we already had a real Double XP weekend last week, this time around, you'll only earn extra experience for your weapons, which now have the ability to prestige in Black Ops II.
Since most of you probably have maxed out weapons, feel free to prestige them and wrack up levels to your heart's content. It may not be a big deal for most of you out there, but for those who care, you've been informed!