I've been scouring the docs for a while now and can't seem to find a way to accomplish this. The information is available publicly (on a facebook page ... the link says "View all # shares") but I can't seem to find a way to access this info either via FQL or the graph API.
I know I can get a list of likes for a given post:
https://graph.facebook.com/87236249496_134765166623967/likes
The goal is to get a list of people who've shared -- but there doesn't seem to be the same sort of thing for shares. Am I missing something?
Go to... http://www.facebook.com/ajax/shares/view/?target_fbid=10154612868272801&__a=1
10154612868272801 is Facebook story ID, __a stands for asynchronous.
You will see large amount of text/JSON, it is basically HTML & JS for little popup window. There is portion of text like hovercard.php?id=# where # is Facebook user ID, using preg_match_all you then get all of the user ID's who shared that post.
Eg: 100000541151971 (Eric) and 9204448 (Courtney)...
Unfortunately, you must be logged into Facebook to do first step, figure it out :)