Jailbreak iOS 4.2.1 And Install OpenSSH Using Redsn0w 0.9.6 Beta 3[How To Guide]
iPhone Dev Team has released Redsn0w 0.9.6 Beta 3 to support iOS 4.2.1 GM IPSW.You can jailbreak iPhone 4, 3GS, 3G, iPod Touch 4G, 3G, 2G, and iPad using Redsn0w 0.9.6b3.However this is a tethered jailbreak for all devices except iPhone 3G, iPod touch 2G (MB), and iPhone 3GS (old bootrom).