In other words, he is incredibly careful, and that's a good thing. With his tools, you can hack any firmware release for your Playstation 3. You do need to compile from source, which should work on any Linux machine or Macintosh. After compiling his code, run
./create_cfw.sh PS3UPDATE.PUP CFW.PUP, and put the resulting file on a USB drive in
PS3/UPDATE/PS3UPDAT.PUP. You can then install the hacked firmware from within system update on the console.
The feature set of the hacked firmware is limited: all it does is add "Install Package Files" to the Game section of the Playstation 3 user interface. This will eventually allow you to install signed executables (using homebrew .pkg files). These executables will be signed using the recently uncovered keys.
What it will not allow you to do is run pirated games. While someone else will surely implement this 'feature', KaKaRoTo will not. "Since the kernel is left unmodified, this means that this custom firmware is really meant for future homebrew installation, and it will not allow piracy. I plan on keeping it that way," he writes on his blog.
It's about time the Playstation 3 was cracked wide open. Sony is of course free to ban hacked consoles from the Playstation Network, but PS3 owners are also free to install whatever they want on their consoles.