Gmail just picked up another desktop-like drag-and-drop feature, less than a month after giving attachments that convenience.
Starting in Chrome, and coming to other browsers soon, you can now drag pictures into messages to embed them in a message.
You don't even need the "Inserting Images" lab enabled for drag-and-drop picture insertion to work.
Simply drag an image to the spot where you want it, click the "Change image" link to resize, if needed, then finish up and send it on its way.
Image: Google Blog