There is an unofficial version of QuickPwn floating out there so be careful.
Please go here for the latest announcement: Dev-Team Blog - Cat. Bag. Mouse.

Taken from the blog:

THE MOST IMPORTANT THING ABOUT THE UNOFFICIAL QUICKPWN RELEASES IS THAT IF YOU USE THEM, YOU WILL KILL YELLOWSN0W, POSSIBLY FOREVER. That’s because QuickPwn, by its very nature, requires you to already have accepted Apple’s official IPSW, along with its baseband update. If you do that, you will (possibly forever) lose your ability to software-unlock your iPhone 3G.
They say that imitation is the sincerest form of flattery, and so perhaps we should be flattered that so many ad-supported sites are now using our own tools to create unofficial jailbreaks (QuickPwn in particular is so easily adapted from one release to the next that it’s reduced to a handful of binary pattern searches in a good hex editor). But please don’t expect support for them on this blog, because we’re actually busy with the hard part of the 3.0 jailbreak (the 02.28 incompatibility and the new compressed ramdisk they’re using).
Oh, and also the unlock

Does this quickpwn activate your phone for unofficial SIM cards (not unlock but only activate as i have a 2G iphone)

Correct me if I am wrong, but is using the unofficial quickpwn only harmfull to the yellowsn0w process? I am legal AT&T user, and have no use for the unlock but love to customize the iPhone

what part of the Dev Team's that you don't understand ?

Originally Posted by mfleigle

Correct me if I am wrong, but is using the unofficial quickpwn only harmfull to the yellowsn0w process? I am legal AT&T user, and have no use for the unlock but love to customize the iPhone

seriously? read the blog again man... if you use this unofficial quickpwn, you may lock yourself out of ever being able to modify (read: unlock) your phone again so as always, use at your own risk.

"THE MOST IMPORTANT THING ABOUT THE UNOFFICIAL QUICKPWN RELEASES IS THAT IF YOU USE THEM, YOU WILL KILL YELLOWSN0W, POSSIBLY FOREVER. That’s because QuickPwn, by its very nature, requires you to already have accepted Apple’s official IPSW, along with its baseband update. If you do that, you will (possibly forever) lose your ability to software-unlock your iPhone 3G."

enkrypt3d, If you read what mfleigle posted, he said that he is a legit AT&T user and has "no use for the unlock" and all he is interested in is knowing whether he can use the 'unofficial' (see: not provided by the Dev Team) jailbreak to customize his iPhone.

So, to answer your question...
Yes, you can use the 'unofficial' jailbreak to customize your iPhone. At this point, there do not appear to be any other issues caused by the jailbreak that have been publically discussed. There are definitely plenty of issues with applications that work just fine under the 2.x iPhone OS builds that no longer work (at all in some cases) under the 3.x iPhone OS builds.

Although, I guess the QuickPwn jailbreak process is more what is potentially damaging to the unlocking process as it is dependent on jailbreaking a pre-upgraded version of the iPhone OS rather than the 'unofficial', double-unsanctioned jailbreak provided for 3.0b2.

~Adrian

There is a version of quickpwn3.1 for Windows that some one is posting on the net...Yea, don't download it... Backdoor.IRC.Zapchast.zwrc is in it... just an FYI... guess there is nothing for us Windoze (Sigh!) users, yet. Patience...
it has an Icon that looks alot like the "Flash" logo from Adobe - Yea, it's bogus.

Admin, maybe add this to the Sticky above