iTunes 7.4 Blocks AT&T-free iPhone Activation Hacks

Several readers reported that the new version of iTunes 7.4 blocks iPhone activated by another procedure than the one designed by Apple and AT&T.
Those hackers successfully activated the iPhone without modifying the firmware of the iPhone, after iTunes 7.4, one can use the iPhone on a non-AT&T network. iTunes updates even deletes some ringtones installed after hacking the activation procedure.
So Apple fired back, and hackers will have to further refine their procedures to maintain AT&T-less activation possible.
[update]
According to Frenchiphone forum, iTunes 7.4 simply prevent Jailbreak to run (allowing automatic activation of iPhone independently of an AT&T network)
[update2]
New tools to be used only with iTunes 7.4 are now available:
http://www.winandmac.com