Now attach photos from Auto Backup in Gmail

As of today, you can attach photos from your Google+ Auto Backup folder to a message in Gmail.

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
Thanks to the Google+ integration, you can also insert whole albums straight from your Google+ Photos collection. Old functionality hasn't been cut out of the picture (pun very much intended), photo uploading the old way and inserting images from URL seems to be here to stay, or for at least a little bit longer.

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
Google notes that the update is rolling out over the course of the day so if you don't see it yet, no need to panic.

Source & Images: Official Gmail Blog