Facebook today updated its Slingshot chat app to make its bold, pay to play mechanic optional. If youre not familiar with the app, until today, Slingshot asked you to send a photo before you could unlock the one you just received. With the mechanic turned off, Slingshot is effectively a much more straightforward clone of Snapchat — you can send off photos and videos that disappear after friends have seen them. Slingshot didnt need to succeed — its an experiment borne of Facebooks Creative Labs skunkworks division — but with todays update, Facebook seems to be saying that this experiment has failed.