For those interested in running backup games on your PlayStation 3, a clever chap called George Hotz has (apparently) managed to slip a crowbar into a wall of the chunky black fortress.
He posted his success on Australia Day (Jan 26th) 2010 on his blog post. The post also includes a link to the source code he used to compile the exploit, allowing full memory space access.
He's posted a link to how it works (for the less tech savvy) and a more detailed technical post here for those interested in using the exploit.
