The iPhone Dev-Team has updated RedSn0w to fix Bluetooth issues with the ‘Backup Plan’ untether.
The fifth beta is now available (testers ONLY please!). Bluetooth is now working (and any sandbox-related issues should be resolved too). Please do not pirate the 4.2b3 IPSW! Only those enrolled in the iPhone Developer program have legitimate access to that IPSW.
There is actually a Windows version of beta5, but it’s excruciatingly slow compared to the Mac version because it’s forced to use files on your hard drive instead of RAM while it’s processing the very large IPSW images. It really is very very painfully slow, so we probably won’t be releasing it for testing purposes unless it can be sped up somehow.
You can download RedSn0w .0.7b5 from here. You can find instructions on how to use this version of RedSn0w to untether here.