iPhone 4

jailbreak

iOS 4.0/4.01

Jailbreak iOS 4.0/4.0.1 using jailbreakme.com

iOS 4.1

How to update to iOS 4.1 without updating the baseband

Jailbreak iOS 4.1 using limera1n

Jailbreak using redsn0w 0.9.6 beta 2 for Windows/Mac