The Chronic Dev Team have confirmed that they will release GreenPois0n rc5 within a few days. The new GreenPois0n rc5 will jailbreak all iDevices on ios 4.2.1 but not much is known on this. For those who are worried about having their SHSH's saved, the Chronic Dev Team have said that you won't need them. Watch the GreenPois0n rc5 demo at here, or below. So this must mean a simple, untethered jailbreak for ios 4.2.1 is on the way... Source [UPDATE] A recent tweet by p0sixninja states that Greenpois0n rc5 is 90% complete.