There are a number of posts out there saying that jailbreak or pwn’ing does not work on the new macs. Well, its not the new Macs per say, but seems to be the new version of iTunes. 

..from iPhoneOverdose

The problem is that the Mac does not recognize the iPhone when it restarts on how DOMs, the amendment needed to install the operating system’s iPhone.

Unable to recognize pwnage tool can not send the amendment, so the only thing you have left is to restart the iPhone and restore a backup.

Now I have read a comment from somewhere saying its a new subversion of iTunes on not the OS itself. Bloody annoying, but such is war. To get iTunes to read the amendment will mean fooling the iphone into thinkings its an upgrade or restoring a backup. Should be interesting. 

So just to be safe till we understand this more, I would not update iTunes anytime soon.