iOS 5.0.1 Beta was released to developers on November 2nd. In no time at all the iPhone Dev Team was able to jailbreak the new firmware. They said that the latest version of redsn0w will work for the jb.
Keep in mind the jailbreak is tethered, so you will need to plug your iOS device into your computer each time you reboot the device. Here is the update posted on the Dev Team Blog:
Update #16: redsn0w version 0.9.9b8 will natively recognize the 5.0.1 beta that Apple let developers start testing this week (so you don’t have to play the “point at 5.0 IPSW” trick). Because the IPSW isn’t public, you’ll still need to provide it once to redsn0w (at which point it will cache all the important pieces so you don’t need to select it again).
For those 3GS and i4 users who preserve their baseband, the Mac version can also produce the NO_BB_* custom IPSWs for 5.0.1. (But please note that ultrasn0w doesn’t get updated for betas like this.)
This is still a tethered jailbreak for all except old-bootrom 3GS users.
Keep in mind that iOS beta builds are not available to non-developers. You must register for a developer account, which is $99 a year. Otherwise, one cannot obtain it through a legal means. The iOS 5.0.1 beta is coming in the near future as a fix for the bugs causing the battery life issues with some iOS devices.
For those who aren’t fans of tethered jb, there is a semi-tether option, which allows you to boot your device in a non-jailbroken state, then you can do a tethered boot later to get your jb software running again. Furthermore, ion1c is working on an untethered jailbreak, which may suit those who don’t mind waiting a bit longer.
The download links for redsn0w are right here. These are straight from the Dev-Team blog: