The Xbox 360 version of Minecraft has seen mash-up packs in the past that introduced content from other titles--including Mass Effect and Skyrim--into Mojang's sandbox building game. This content included new music, menus, worlds, and character skins, as well as updated items.
Based on the single screenshot shared with today's announcement, it looks as if the same type of content will be included when this new Halo crossover hits. We can see a player using a Master Chief skin (and holding what looks almost like a Needler), computer screens built inside a structure, and part of a Halo ring extending up into the sky.
Microsoft's Phil Spencer announced last month that saves from Minecraft Xbox 360 Edition would carry over to the Xbox One Edition, which is not yet available. In March, Spencer said the next-gen version was "really close" to being complete, and just this week he said a release date was close to being finalized. Whether DLC, including this new Halo content, will carry over or be available in the Xbox One Edition has not been announced.
Minecraft has sold remarkably well on every platform it's come to, having recently surpassed 12 million sales on the Xbox 360 and 15 million on PC. More than 1 million copies were sold on the PlayStation 3 during its first month of availability, and upwards of 21 million copies have been sold on iOS and Android. The game's total sales will grow even further later this year, with PS4 and Vita versions set to released by September.