Currently, iBooty 2.0 is being tested out by certain iPhone users and after getting positive feedback we can expect the release of Sn0wbreeze 2.2 for iOS 4.2.1 in next few days.
ThePirate who is also testing iBooty 2.0 has just confirmed the same on his twitter account:
For those iPhone users who don’t know, Sn0wbreeze tool is used to cook custom firmware for iDevices on Windows Operating System. The current Snowbreeze 2.1 version supports up to iOS 4.1 firmware on iPhone and iPod Touch and iOS 3.2.2 on iPad.
For Mac users PwnageTool with iOS 4.2.1 support is already available.