NBC’s Brian Williams will co-anchor NBC’s Today show in the morning alongside Matt Lauer, “so Meredith can take a morning off,” he announced on tonight’s Nightly News.

One of the last times Williams was on the show live and in studio was when he appeared with former Today co-anchor Katie Couric and ABC’s Charlie Gibson to promote last summer’s Stand up to Cancer event.

> Update: Meredith Vieira won’t be on the Today show tomorrow, but a tipster tells us she’ll be on The Tonight Show instead.

> Morning Update: Williams co-anchored just the first hour of the show. He moderated a debate between CNBCers Rick Santelli and Steve Liesman saying Santelli’s call yesterday for a remake of the Boston Tea Party was, “the most e-mailed moment in the Blogosphere.” (Santelli: “Maybe I could have chosen some words better, but I think at the end of the day, what this boils down to is you have to treat everybody fairly.”) Later in the show the control room cued up, “It’s Raining Men” as Lauer and Williams sat side by side in studio and Al Roker reported from Miami Beach.