Taimur Asad of Redmond Pie is reporting that if you have an iPhone 3G that relies on Ultrasn0w unlock don’t download Redsn0w. This is because it updates your baseband to the latest version, which for the time being makes it impossible to unlock.
Owners are advised to do this jailbreak at their own risk only. This download is a beta release for the devices at FW 4.0 or 4.1, and it has the same pwnage2 DFU-mode exploit which has been used since the 2.x days. The SHAtter exploit developed by pod2g is not included in the download.
Those of you who have the iPhone 4, iPod Touch 4G, iPad, and Apple TV 2G will have to wait until Sunday to jailbreak iOS 4.1 when GreenPois0n is released.
Also See: iPhone data eraser for Mac and Windows