If you intend to jailbreak iPhone 4 then you need to have the right software application to do exactly that. There are many software applications online, this means that finding one wouldn't be an issue to many individuals. However, you do not want to be among the harrowing statistics of jailbreak went wrong iPhone users. The fact of the matter is that it is not as easy to find a reliable software provider as we would like to believe. You will need to be cautious enough and get a provider who has received sufficient positive feedback from others.
sources: