Sometimes it’s useful to draw someone a sketch to help explain something in an online chat – draw someone a map to your place, describe the shape of the plug socket for which you need a lead, and so on.
Google has started to roll out a tool in Hangouts’ interface that lets you doodle such little drawings. If you already have it, hovering over the camera icon will display a new pencil icon:
Clicking on the pencil launches the new tool. It’s very basic, but should be enough to add annotations to an image or draw a small diagram.
UPDATE: If you don’t appear to have it yet, it seems that uninstalling the Hangouts extension for Chrome and then reinstalling it will activate the feature.