Getting Facebooks' Cover Photo via PHP SDK & Graph API

I think the easiest is to use the graph api:

http://graph.facebook.com/{user_id or page_id}?fields=cover

and parse the returned JSON.

{
  "cover": {
    "id": "XXX", 
    "source": "https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash4/311205_989690200741_1231438675_n.jpg", 
    "offset_y": 66
  }, 
  "id": "XXXXXX"
}

Facebook seems to have added the Cover field to User Object recently

https://graph.facebook.com/facebookuserid?fields=cover will give you the user cover pic Details

Facebook Doc Link : http://developers.facebook.com/docs/reference/api/user/