Mac Owner? Wann Try the Untethered iOS 4.2.1 Jailbreak?

I know that most of your are waiting eagerly for the untethered jailbreak solution on iOS 4.2.1 for new-generation iOS devices. As most of you know, the iPhone Dev Team already has the backup plan to achieve iOS 4.2.1 untethered jailbreak for Christmas Eve.
Just a few minutes ago, the iPhone Dev Team has confirmed the release of untethered iOS 4.2.1 jailbreak for the Christmas Eve and asking for Mac OS X owners to help them with testing the the backup plan.

Over the Christmas weekend we’ll be releasing a version of redsn0w that implements the “backup plan” to the 4.2.1 untethered jailbreak. We’re seeking your help to test this redsn0w and find any bugs before we do a general release!

(If you have an iPhone 3G, or an old-bootrom ipt2g or iPhone 3GS, you already have an untethered jailbreak! Just use the latest public redsn0w.)

To keep things manageable, this will be a Mac-only test program. We also request that any volunteers *NOT* need the ultrasn0w unlock (in case things go very wrong).

Right now, the “backup plan” requires that you have the 4.2b3 IPSW on your Mac, and that Cydia has your 4.2b3 SHSH hashes. Please don’t pirate that 4.2b3 IPSW! (We’re also working on a way that this technique might apply to all those with 4.1 IPSWs, but that’s not the first goal right now.)

To survive in this, you must be a Mac owner, got iOS 4.2 beta 3 SHSH blobs on your Mac or that Cydia has your 4.2b3 SHSH hashes that was automatically saved (in the status bar), and have a new-generation iOS device (i.e. iPhone 4, 3GS, iPad, iPod 4G, 3G).

If you fit all the above qualifications, so you can follow @redsn0w_testers on Twitter and give the Dev-Team a comment in this post to get the backup plan right now ! Let us know how does it go with you. Also stay tuned for a Christmas launch for public