Big news last week, when the CJEU determined that dynamic IP addresses could be designated as personal data - including the conclusion that Service Providers who hold information on the users behind such addresses may now be obliged to disclose that information. Read a more detailed article from the good people at Hunton & Williams here: http://tinyurl.com/zp59wjf.
To date, static IP addresses had been considered personal data, since they were attached to an account holder's billing or postal address. With the disclosure net now cast across dynamic IP addresses as well, the identity of most users of internet services can be identified - if not directly, then in conjunction with other data that might be available.
I suspect we will be hearing much more about this once it is tested in the courts!