Please read about the history of jailbreaks before posting anything next time.
Apple have always patched the current jailbreak-solution with the next big release of iOS, in this case they patched it due to
You must login or register to view this content. PDF exploit and the release of the source code in the leaked version which gave a very briefe tutorial on how the exploit worked, this made it possible to "
anyone" to make their own PDF, which could have been a virus which destroyed your iDevice. They have
not succesfully stopped the jailbreak, if so, only for the iPad 2, the iPhone Dev-Team for example released the jailbreak for iOS 5b4 yesterday, all current devices are pwned for life due to the "limera1n exploit", the iPad 2 have patched that hardware exploit, that is also one of the reasons they released 4.3.4 so fast, they want to keep it locked down as long as possible.
Last year Apple released iOS 3.1.3 which patched the current jailbreak solution and unlock solution, thay have always been out to patch all jailbreaks asap.
I'm not talking about OpenSHH, which I'm assuming you have done for your friend. I'm talking about viruses and other unsigned code that can destroy your iDevice.