Sony releases Firmware version 1.51 for Japanese Sony PSP consoles.
The announcement says that it is not required to apply this update. It fixes security issues. Sony is not going into details on what those security issues are, but I guess they are related to the news about people hacking the UMD format and trying to play hacked games from memory stick. As long as new Firmware is not providing more features like a web browsers nobody will apply it though.
More details on the Sony Playstation Japan site (Japanese) and on Lik-Sang.
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