Microsoft confirmed in a status update on Twitter today that their acquisition of Mojang Studios, and specifically of the Minecraft IP, has been officially closed:
It’s official, today we welcome Mojang to the Microsoft Studios family. We’re excited for the possibilities ahead w/the Minecraft community.
— Phil Spencer (@XboxP3) November 6, 2014
Microsoft had previously announced the deal back in September, but this tweet confirms that all loose ends have been tied up and the business deal has been completely settled.