Back in the 1.x days JailbreakMe.com was the simplest way to jailbreak your device. And now comex and Dev-Team have released the latest userland jailbreak which exploits a PDF flaw in MobileSafari. This means you can jailbreak any iOS device, including the iPhone4 on the 4.x firmware. Because the exploit that was used it public I’m sure it won’t be too long until Apple fix the flaw and then a new exploit will have to be used. As always remember to backup your SHSH files so that you can restore to your current firmware and keep on using JailbreakMe.com in the future.
To jailbreak just open up the site JailbreakMe.com and then slide to jailbreak and then just wait. It’s that simple!