I have my phone JB/unlocked on iPhone 4 and the features on 4.2.1 just aren't worth me reinstalling everything I already have and to find some stuff likely broken. limera1n worked well for me. Didn't most people snatch up 4.0.1 jailbreakme.com or 4.1 limera1n/GP? still always glad to see the scene jailbreaking the "latest and greatest" firmwares. Progress is great.