Minecraft, whose sales just topped 100 million is not going to go the same path as some XBox games with in game advertising or sly nods to product or brand placements within environments. Mojang, maker of Minecraft and subsidiary of Microsot, said in a blog post, that advertisers or brands will not be allowed to build or promote their products in the Minecraft environement but users can continue to build whatever they want provided it isn't aimed at promotion.
Minecraft is purchased by user license and enables access to the services and various servers where users can build and create environments. Microsoft, who purcahsed Minecrat in 2014 for $2.5 billion, used to allow advertising in XBox 360 games as billboards could show brands, upcoming movies or even, famous politicians. Since Mincecraft is a paid product and one that caters to younger users (and will soon be launched in China), there's really no place for ad placements or the furthering brand objectives.