Gmail allows you to share image attachments with other Google+ users by clicking the "Share" link, but what about the embedded images from a message? Now you can share them by mousing over the images and clicking the "share" button.
How to insert images into a Gmail message? Just drag and drop the images from your favorite file manager. It should work in the latest versions of Chrome, Safari and Firefox, assuming that you haven't disabled the rich text mode.
{ Thanks, Enrico. }