Yesterday I wrote an article in which present some information published on the Wikipedia website about the following untethered jailbreak solution for iOS 4.2.1 called greenpois0n RC5. Information appeared on Wikipedia indicating that greenpois0n RC5 will perform untethered jailbreak on all devices except iPhone 3G. Last evening, Pod2G from the Chronic Dev Team confirmed this information on Twitter, indicating that greenpois0n will work with the same devices with which it has worked since its first release, and the iPhone 3G is of course excluded from this list.
For the iPhone 3G, there is anyway redsn0w that does untethered jailbreak, so you have nothing to fear. Pod2G reconfirms that greenpois0n will work without any SHSH from Cydia and you can jailbreak even devices that came with iOS 4.2.1 installed from the factory.
