During the last evening the Dev Team updated the article regarding redsn0w 0.9.6 beta 4 including some clarifications about the tethered/semi-tethered jailbreak ONLY available to iPhone3GS(new bootrom)/iPhone 4, iPod Touch 2G(new bootrom)/3G/4G and iPad. As I have you explained also yesterday, the tethered jailbreak made on these terminals does not necessarily lead to the impossibility of restarting the phone without restoring the jailbreak, but only to restarting it without the possibility of using Cydia, Cydia and Safari applications. This is one of the good things that the Dev Team managed to do for tethered jailbreak because in certain conditions we will be able to use the phones even if they close suddenly.
However, there is an exception to the above rule, if you install from Cydia tweaks that modify the SpringBoard - mobilesubstrate, activator, or other crazy things - and you close the terminal, then it will no longer boot and will freeze at apple during booting . If you end up in this situation, you can only restart the terminal using the function Just boot tethered right now from redsn0wand an tutorial which will teach you how to boot tethered and use the applications from Cydia you can find here.
My advice is DO NOT UPDATE AND JAILBREAK on iOS 4.2.1 for now if you have one of the above terminals because the situation is quite complicated. If you still update and jailbreak then DO NOT INSTALL TWEAKS from Cydia and you will not be left with the terminal blocked if it closes/resets out of the blue.
I already mentioned a jailbreak tutorial, but I think it should be mentioned again, Windows 7 users MUST to run redsn0w in compatibility mode with Windows XP.
