"So, back to our initial question: is an IP address personal data, or, in other words, can you figure out who someone is from an IP address? A black-and-white declaration that all IP addresses are always personal data incorrectly suggests that every IP address can be associated with a specific individual. In some contexts this is more true: if you're an ISP and you assign an IP address to a computer that connects under a particular subscriber's account, and you know the name and address of the person who holds that account, then that IP address is more like personal data, even though multiple people could still be using it. On the other hand, the IP addresses recorded by every website on the planet without additional information should not be considered personal data, because these websites usually cannot identify the human beings behind these number strings."
http://googlepublicpolicy.blogspot.com/2008/02/are-ip-addresses-personal.html
I guess this is one of many source I could have stated.
