Gwen Stefani has confirmed that she will indeed be replacing Christina Aguilera on The Voice 'coaching' lineup for the next 'season'.
(That's the one in America, obviously).
The news leaked a few weeks ago but the whole thing was confirmed by the show's host Carson Daly during the show.
"This all just happened moments ago because we're live, and we're very happy to officially announce that two superstars will be joining the next season in these coaches' chairs: Pharrell Williams and Gwen Stefani will be added to the Voice family," he explained (as quoted here).
It's thought the delay in officially announcing Stefani's arrival was because she was still debating about whether to do The Voice or a new talent show, Rising Star, which premieres in the summer.
Apparently Stefani will perform 'Hollaback Girl' on the show on May 5 as a way of introducing herself.