IPREDator is clearly a response to the introduction of IPRED in Sweden, which will allow law enforcement and copyright holders to request the personal details of suspected infringers. The copyright holders will then be able to make direct contact with the accused users and presumably threaten them with lawsuits.
If users connect to The Pirate Bay through something like Tor or VPN, however, they're less likely to be tracked. IPREDator's website says that it won't store any traffic data, as its entire goal is to help people stay anonymous on the web. Without any data to hand over, copyright owners won't be able to find individuals to target."