How to add Like box to your app on Facebook
For some reasons, Facebook doesn’t want to fix “Like it” box so that it will be easily integrated into your Facebook application page. So, there is a workaround, which allows you to place Like box for your application into your app page.
In this case I got a part of the iframed page http://www.facebook.com/connect/connect.php?id=127104720672096, there id – is your application’s id.
See, how it looks in my app https://apps.facebook.com/jbirthday