The Apple iphone 1.1.3. firmware has been jailbreaked.
You can get more info on: Ziphone
To do so, you don’t need to downgrade you iphone!
It seems to be the easiest way to jailbreak your iphone!
Disclaimer: My Gadget Info is not responsible for any accidental damage that may ensue should something go wrong in this procedure. However, I can tell you that I have performed this operation multiple times with no failure, and that a simple restore in iTunes will bring your device back to factory settings. Also, should you need to bring in your device to the Apple Store or Genius Bar, it’d be wise to restore it before because loading 3rd party software on the iPhone or iPod touch does void your warranty.