mfields/mfields-opengraph-meta-tags — pull request #3 by billerickson (2012-03-21 14:46:24+00:00)
Title: Remove limit of image to post types that support featured image. 

This is so that the default image can apply everywhere. You can specify a default image that applies not only to posts, but to pages, categories... any page that someone might like. If you still want it limited to post types that support post thumbnails, add that conditional to your filter.