PS3 Firmware Update 2.43 Released; Mandatory in Japan Only!
To quote Al De Leon (PR Manager, SCEA) via PS Blog:
Hi, everyone, I wanted to give you a heads up about PS3 firmware update (v2.43). Unlike previous updates, firmware v2.43 is specific to the Japan region, and only PS3 users there will be required to install the update. PS3 users in all other regions will not be prompted to download v2.43. However, if you manually initiate a firmware update by clicking on "System Update" under the XMB’s Settings icon, the v2.43 update will be available, regardless of where you are located.
Users outside of Japan do not need to perform this update if your PS3 system software is on version v2.41 or later. However if you do perform the update, it will not cause any issues with your system or add any new functionality. More PlayStation 3 News...