I guess you know that 10.5.6 update is here.Although i dot’t have a mac 🙁 , I got literally invaded with this news. But guess what? This update has been found to cause your Mac to stop recognizing your iPhone while in DFU mode, making it impossible to jailbreak and/or unlock it using PwnageTool or QuickPwn. If you need to be able to hack your iPhone or iPod touch for any reason, we suggest you do not update your Mac to 10.5.6 unless you really need to. The Dev Team has been informed of the issue.
Do not update untill the dev team finds a solution.
Install Windows on your mac .
Later edit :
HOW TO FIX IT
- Replace the following plugin kexts from within IOUSBFamily.kext with the ones from 10.5.5 and then rebuild kextcache (if you don’t understand this, then you shouldn’t attempt it!)
- Use a USB hub in-between the DFU device and the Mac and insert/reinsert the iPhone’s USB cable.
- Use a PwnageTool created .ipsw on Windows! Oh the irony!