I sniffed some Outbrain traffic (e.g. on CNN, find the file called "get" under "odb.outbrain.com/utils" in Chrome's network tab), and found this P3P header:
P3P:policyref="http://www.outbrain.com/w3c/p3p.xml",CP="NOI NID CURa DEVa TAIa PSAa PSDa OUR IND UNI"
The link to http://www.outbrain.com/w3c/p3p.xml returns a 404. Does this have any implications? How would browsers (IE mostly, I guess) treat a P3P header that links to a missing P3P file?