It took a long time, but it's finally here - the ability to add photos from your Auto Backup folder to a Gmail message. That's all thanks to the new Insert Photo button which can be found on the toolbar at the bottom of the compose window in Gmail on the web. As you most likely already know, Auto Backup is a Google+ feature which automatically uploads the photos and videos you take on your mobile devices and uploads it to a private folder which only you can see.
|Look for the Insert Photos button to get started|
Also announced today is the ability to resize images while composing your message, just drag the handles to resize as you please.
|Select individual photos, or whole albums|
Source & Images: Official Gmail Blog