The software is called ZiPhone and it is the first true jailbreak for 1.1.3. It is now safe to upgrade to 1.1.3
I upgraded to 1.1.3 last night and it’s working great!
Be careful though, ZiPhone is buggy!!
ZiPhone 2.0 has a bug that will get your phone stuck at the bootloader
ZiPhone 2.1 has a bug that will crash your phone if you delete the ZiPhone blog WebClip
ZiPhone 2.2 has a bug that the ZiPhone-Gui does not work (wrong files included in the package)