Google said it would do it, and now it has. The latest update to Android's Gmail app has enabled images automatically, now made safe because Google is serving up the images after hosting them on its own proxy servers. Users will no longer need to tap the "show pictures" message above the email content.
Left: old style. Right: 4.7.2.
We're looking through the application now to see if there are any more changes - this thing is so fresh that Google hasn't even updated the Play Store description.