While it used to be the case that a link could only have a small (90x90) picture, it appears that links can now have larger pictures (e.g. 400x208) in your feed.
You can see this if you paste a link that has a large og:image into the "Update Status" field on the Facebook UI (e.g. http://allthingsd.com/20131003/facebook-tries-to-make-home-more-inviting-by-welcoming-photos-from-other-services/ )
It also seems that some 3rd party apps are able to post a link to your feed as well - For example, if I post the above link with HootSuite the picture appears in the large size.
But, when we've tried it with the graph API, we can't seem to get anything but the small 90x90 pictures with a link.
When using the Graph API, does anyone know what fields need to be passed into /me/feed (or /me/links) in order to get the bigger picture? It doesn't seem that link, title, description, and picture is enough - the picture still ends up being small in this case.
Thanks!