The iOS SDK 4.1 beta was just seeded to developers a few hours ago and believe it or not, you can already jailbreak it. The Dev Team didn’t even have to do any work on the now famous RedSn0w as the 0.9.5b5-5 version can jailbreak iOS 4.1 beta.
Instructions to jailbreak your iPhone iOS 4 with RedSn0w remain the same. However, remember this is still a beta version. To date, this version of RedSn0w is only compatible with the iPhone 3G and iPod Touch 2G (non MC models).
Also remember that iOS 4.1 beta is called “beta” for a reason. It is released for developers and the general public should stay away from it.