This is a plugin to add Open Graph Protocol Data to the metadata of your WordPress blog.
Go to http://www.facebook.com/developers and allow the developer application access to your account. As of writing this, there is an issue with this and you will be presented with an 404 error after it redirects you back to facebook. - Screenshot 3
Go to http://www.facebook.com/developers and click on the right hand side click on +set up new app if you get the 404 error. - Screenshot 4
If this does not work, go to http://www.facebook.com/developers/createapp.php - Screenshot 5
Fill in the form, click create application - Screenshot 6
On the left hand side click on Web site and your application id should be there! - Screenshot 7