According to a report by John Leyden at theregister.co.uk ,the hackers uncovered the hack in order to run Linux or PS3 consoles, irrespective of the version of firmware the games console was running. By knowing the private key used by Sony the hackers are able to sign code so that a console can boot directly into Linux. Previous approaches to running the open source OS on a games console were firmware specific and involved messing around with USB sticks.
Fail0verflow hacking group released more information about the crack during the annual Chaos Communication Conference in Berlin.
More information is available here.