It seems that Facebook is not handling properly links from our image description pages.
Normally, if one would share http://commons.wikimedia.org/wiki/File:Mostar_Old_Town_Panorama_2007.jpg (today's picture of the day) on Facebook, they would expect their post to have a picture and hopefully some snippet from the image description. Unfortunately, one gets a dry link without any pictures or relevant text.
Sharing Commons URLs not ending in a file extension (e.g. the main page) results in a nice post with a picture taken from the given page.
As far as I can see Google Buzz exhibits the same problem, but given that we have a special relationship with Facebook -- if others can replicate the problem -- we should contact them about this: I'd like to share the picture of the day every now and then and have my friends marvel on the picture without having to click through the link.