The Dev-Team has updated their blog with a little snippet about the blackra1n jailbreak. Below is what they have to say. You can see the original article HERE.
Update: geohot released a Windows jailbreak called “blackra1n” which is similar to redsn0w in that it covers multiple devices (and it covers beyond just firmware 3.0.1 where redsn0w currently stops). blackra1n is not a carrier unlock. You must always avoid updating your baseband to maintain your unlockability. If you use blackra1n to jailbreak 3.1 or 3.1.2, the steps you take before running blackra1n will prevent the unlock from working on your iPhone for potentially a very long time. By the way, we haven’t yet tested whether a blackra1n’d device can accept a custom IPSW without tweaks, but if it doesn’t then it should only require a minor change.