Sony has updated PlayStation Portable firmware to version 3.51 after hackers found a way to bypass security in its most recent update and downgrade firmware.
The virtue of doing that from a hacker's perspective is that older firmware is capable of running homebrew applications and - the bit Sony worries about - pirated games.
PSPUpdates.com, which follows the homebrew scene and associated hacks closely, explains that all the exploit entails is getting hold of a copy of Q Entertainment's Lumines, unzipping some files onto a Memory Stick in a certain directory, and then pressing the Start button at a certain point during the game's initial load sequence.
The latest firmware drama marks yet another turn in a running battle Sony has been conducting with hackers ever since the PSP launched in December 2004. Previous hacks have included an exploit built around Grand Theft Auto: Liberty City Stories - the PSP's best-selling game to date - and the game was subsequently patched and re-released by published Take-Two.