Read on for a simple description of a simple new feature...
Gmail's site describes it as:
"It's like seeing the trailer before you see the movie. Now you can get a sneak preview of your attachments."
Gmail now adds the ability to preview graphic images attached to email messages you receive by displaying "thumbnails" of the images displayed below the message text. In many cases, you won't even need to open the image, but you still have the familiar "View" and "Download" options.
Yet another step forward in Gmail's ever-evolving interface!