matrix_jan - 5:06 pm on Dec 14, 2011 (gmt 0)
so is it a Facebook Page or a Group?
Make sure, whichever it is, that in the settings it's marked as available to the public.
Facebook Pages(if available to the public) are accessible to non registered visitors (try /facebook), and so are Groups (e.g. webmasterworld group, /group.php?gid=2410313300).