At present time, the software has only been tested to work on OS X Tiger on Intel chips. A PPC version is said to be under development, but there’s no word about a version for Windows users. Still, I doubtful that they have been left out of the hacking process
The new iJailbreak application has been written by a 13-year old who calls himself AriX. The 2.5mb app is provided as open source on Google Code and licensed under the GNU General Public License version 2. You can download it from here.