I’m trying about 2 days now to have a like button inside my iframe application, so that if a user presses it, the like appears in his wall like the attached image. 
Whatever i tried didn’t work (no title, no image, no description).
Just a “John Doe likes a link” with the url of my app instead of the “apps.facebook.com/my_app”. Like this:
John Doe likes a link
http://www.my_site.com/my_app/
I’ve tried everything. Here is where i am now :
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta property="og:title" content="My title"/>
<meta property="og:type" content="product"/>
<meta property="og:url" content="http://apps.facebook.com/my_app/"/>
<meta property="og:image" content="http://www.my_site.com/my_app/img/THUMBNnighlight.jpg"/>
<meta property="og:site_name" content="My name"/>
<meta property="og:description" content="The Descr Here"/>
<meta property="fb:app_id" content="xxx"/>
<title>My title</title>
</head>
<body>
...
<fb:like href="http://apps.facebook.com/my_app/?app_data=<?php echo urlencode(base64_encode(json_encode($app_data))); ?>" send="true" width="450" show_faces="false"></fb:like>
...
<body>
More than likely the URL is not being read correctly by facebook. See if Facebook can even read the og tags properly by linting the URL you’re having them like.
https://developers.facebook.com/tools/debug