After officially debuting Chromecast outside of the US, Google today announced a new app for the device that allows users to create a collaborative photo montage on their TV screens. The idea is that anybody takes a picture and sends it to a shared “photowall,” creating an instant collage of photos on a big screen which, in turn, can be shared with everybody, across social networks. So although Chromecast has thus far been mostly about streaming video from mobile devices, Google looks to be making a turn to the social in a bid to be more than just a streaming stick – the goal is social control of the living room.