Over the course of the next day or two, Google will be updating the chat function in Google Drive. The chat will be changing from the old colored squares to using everyone's Google Profile Picture. This is part of Google's project to unify all the different chat tools across their products.
New features will include the ability to add people to your Google+ circles without leaving Google Drive, a one-button "Chat with all" button that instantly starts a conversation with everyone in the document.
So be on the look out for the update, it should be a nice change!
Original Post From Google