Update said to stop devices jailbreaking system through USB
By Marc Chacksfield

Firmware update knocks hackers for six
Sony looks to have fixed its jailbreak problem with a firmware update, after it was found that a program was able to get around the PlayStation 3's Fort Knox like protection system and run non-official games installed to an external hard drive.
Although there had been news recently that the jailbreak had hit mobile phones - this was after the PSJailbreak dongle version was banned by Sony - it seems that the games giant has seen fit to add additional "security features" to the PS3 which stops any unauthorised games working on the system.
No longer functional
According to Kotaku, website eXophase was the bearer of bad news to would-be hackers, explaining that "all variants of the USB-hub emulating exploit (PSFreedom, PSGroove, PSJailbreak) are no longer functional".
On Sony's official blog, the 3.42 firmware update is a minor update but one that does add an extra layer of security to the console.
Now that a workaround has been created, it's inevitable that jailbreakers will be going back to the drawing board to create a modified system.
Let the cat and mouse games begin.
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Do not update now guys
Find and install the 3.41 kernel manually