Once you have more than 10,000 reputation, you gain access to various moderator tools (accessible from the "mod" link at the top of the page.
The Moderator Tools page has a separate tab that lists all posts migrated to and away from the site:
http://wordpress.stackexchange.com/admin/posts/migrated/herehttps://wordpress.stackexchange.com/admin/posts/migrated/here
