The new price is for the Xbox One Standard which includes the Xbox One console and one Xbox One wireless controller, it does not include the Xbox One Kinect.
According to Engadget, Microsoft says the new pricing is a UK-only deal which suggests it might be temporary, however considering the price drops in the US the more probable outcome is that this will remain permanent.
Microsoft is leaning heavily on the number of exclusive that'll be launched on the console in 2015 including Halo 5: Guardians, Rise of the Tomb Raider and Forza Motorsport 6.
It's also the only console where you'll be able to get both Fable Legends and Quantum Break.
Of course Sony also has a few tricks up its sleeve with the new Street Fighter game being confirmed as an exclusive along with No Man's Sky and the new Uncharted game.