That's correct, you can't use redsn0w yet (for a stable jailbreak anyway). Redsn0w 0.9.5b5 can jailbreak 4.1 if you point it to the 4.0 firmware, but DONT DO THIS as it screws up the wifi, slide to unlock, and so on... even us 'easily jailbroken' device owners will have to be patient!