The jailbreak the iPhone Dev Team released a couple of days ago is in no way intended to be used by end-users rather than developers. It is a jailbreak-only, that allows Cydia based developers to make their apps compatible to iPhone OS 4.0.
The jailbreak still requires a legal activation via iTunes and a valid subscription. Means: the redsn0w tool will not hacktivate or sim-unlock your devices. If you ain’t a dev, you are strongly advised not to update, got me?