I'm curious to know if multiple images actually show up in the feed. I know they're supported but in not one single case of testing have I seen multiple images show up on the feed. So what the point in having multiple images in the open graph object? Where do secondary, tertiary images go?
An image URL which should represent your object within the graph. The image must be at least 50px by 50px and have a maximum aspect ratio of 3:1. We support PNG, JPEG and GIF formats. You may include multiple og:image tags to associate multiple images with your page.
Doing a test with object debugger clearly shows that they're in there correctly (sans the image type property):
https://developers.facebook.com/tools/debug/og/object?q=http%3A%2F%2Fpluggin.it%2Fs%2FTI4o%2F
(http://pluggin.it/s/TI4o/ - note the OG tags only show up for Facebook user agent)
You may specify multiple images using this markup. The first image matching minimum requirements is the default selection. A Facebook user authoring a status update might select a different thumbnail based on your explicitly-defined images. A hotel might include multiple photos of the property as Open Graph protocol images, allowing the person sharing the story to share a view of the pool or a view of the restaurant.
Basically I know how to get images into the graph, but I can't seem to find where / how they are displayed in new feed. Are apps like Instagram putting images into photo galleries rather than using open graph? Is that how they display multiple images?