A few next-gen Halo tidbits were briefly posted on the Microsoft Store, giving us a couple of details regarding the next adventure of Master Chief.
"In possession of a mysterious data chip, Petty Officer John-117, aka Master Chief, confronts a new battery of challenges and tests in a Herculean effort to stay alive in a galaxy where sentient life is mercilessly hunted. Pre-order the next chapter in the wildly popular Halo series designed exclusively for Xbox One."
The post has since been removed, but before it was AGB grabbed a screenshot. The new Halo is due sometime in 2014, and although the store listed its release date as December 31, 2014, that's almost certainly a placeholder.