It was only a matter of time. Either Lego would license/partner with Minecraft - which at this point seems moot since Minecraft has Microsoft money so why do they need Lego? - or build their own version of Minecraft with Lego:

The game, which is listed as being an early access title on Steam, is single-player only right now and has you exploring the brick world and unlocking new discoveries "from cowboys and giraffes to vampires and polar bears, to steamrollers, race cars, and colossal digging machines!"

More, including a video, over on Polygon.com.