Some users are seeing a new notification when they open up a chat window today - Facebook notifying them that they can now send photos in chat.
"New! Send a Photo in Chat. Choose an image to send instantly," reads the message.
Clicking on the camera icon allows you to upload images from your computer. The photo recipient will be able to click the photo inside the chat box and it will open up in original resolution.
I've reached out to Facebook to confirm that this is rolling out wide and I'll update this article when I hear back.