You should be on an official carrier to do this, as this jailbreaking will not hacktivate your iPhone handset. If you are on unlocked handset please do not attempt to do this jailbreak.
There is a warning from MuscleNerd that you are bound to come across some trouble in the network once you jailbreak iOS 4.1 Beta 2. Wait till Dev Team updates RedSn0w or take your own chances.