@jibberjab currently, og:type and og:image are supported by default and generated according the content of each post, but those are the only available options and they are not customizable "by hand" at post level.

You can find more information here: http://b2evolution.net/man/open-graph

Hi, on this page: http://b2evolution.net/man/open-graph
it reads:

When enabled, the permalink page of a given post (disp=single) will include one <meta property="og:image" content="http:/url.to/your/image.jpg" /> tag for each image attached to it. Additionally, each post will be marked with <meta property="og:type" content="article" /> (as required by FaceBook).

How does it get enabled? I have a test blog in which I've drag-and-drop-attached an image, but when I view the single post view I don't see those tags. The checkbox is enabled for opengraph tags under the SEO page. Is there some bit of code my skin is missing?

@jibberjab this feature works out of the box.

Are you using a customized _html_header.inc.php file in your skin? If that's the case (btw, it is not recommended), you must make sure that the custom file includes this line of code: https://github.com/b2evolution/b2evolution/blob/master/skins_fallback_v5/_html_header.inc.php#L66

Thanks, that was it.