More and more manufactures are supporting it.
At X018, Microsoft announced that a number of games would receive mouse and keyboard support on Xbox One in the coming days. However, it seems like only Razer would offer peripherals that took advantage of the feature, particular when it came to wireless mice and keyboards. Luckily, that doesn't seem to be the case because Corsair just announced that its devices would support the console.
Full story from the WindowsCentral blog...