There is a new tool called Whited00r for installing ios 4.2.1 on old iphones. If anyone has used this tool, please share your experience.

Here is what it says:
WhiteD00r Install iOS 4.2.1 on iPod touch 1G/2G and iPhone 2G/3G with custom iOS 4.2.1. WhiteD00r iOS 4.2.1 runs faster performance speed on iPhone 2G/3G, iPod touch 1G/2G. Follow the guide how to install iOS 4.2.1 on iPod touch 1G/2G iPhone 2G/3G

See More: WhiteD00r for iOS 4.2.1 on iPhone 2G/3G - suggestions ?