Jay Freeman, better known by his pseudonym saurik as the creator of Cydia, gave a very interesting interview for the site of Make It Work. In an interview in Make it Work , “a relieved important American publication,” Jay talks about the jailbreak and displays his jailbroken iPhone 4, Saurik also mentioned that jailbreak is coming soon and will be free. Saurik also demonstrated Cydia installed on iPhone 4. Obviously, having Cydia is the result of a jailbreak.
BTW Have you noticed on his shirt? puts the same thing when loading Cydia: “Reloading Data”