Over here you can find the instructions for a windows based jailbreak of 1.1.3!
This is what Nate says:
Now you may be wondering how this jailbreak works. Here’s a breakdown:
- iBrickr grabs the 1.1.3 iPhone firmware image and extracts, decrypts, and decompresses the disk image.
- Then it applies a patch, jailbreaking the disk image and activating it, and also installing Installer.app.
- It uploads this new modified image to the phone, as 113_upgrade_image.bin.
- The “1.1.3 soft upgrade”; app flashes the phone with the image and reboots.
- You have a perfect, jailbroken, upgraded 1.1.3 phone, with all your settings and music intact!
UPDATE: THERE NOW IS A MAC BASED JAILBREAK TOO! (same page)