While trying to share my own delightful endless loop of a kākā at a feeding station with a Facebook friend, I realized that Mahara doesn't provide the OpenGraph tags necessary for Facebook to show the images on a Page in its preview.
So, we should add those.
The most important page to do this on is the main Page display, /view/view.php . It would also make sense to do it on /artefact/view.php (for image artefacts), and possibly on the Profile page, and any other pages that can be publicly accessible which I may have forgotten (perhaps the Site home page for logged-out users?)
Probably the cleanest way to do this is to add a function to the artefact API (and/or the block API?), which asks each one whether it wants to post any OpenGraph tags. It would also make sense for the Images to use their "preview" image (the one you see on artefact/view.php) rather than the image itself.
If you're curious about the delightful endless loop of a feeding kākā: https:/ /mahara. org/user/ aaronw/ endless- kaka ;)