How To: Jailbreak PS3 on 3.66 only
Website:
http://www.jailbreakblog.net/

STEP 1: Plug a USB stick into your computer
STEP 2: Create a folder in the root of the USB stick called PS3
STEP 3: Create a folder inside the PS3 folder called UPDATE
STEP 4: Download PsgrooveV1 Tool http://www.mediafire.com/?1vti2tnd1uhec2x
STEP 5: Run as Administrator and click on generate button it will generate PS3.66JBUPDAT.PUP
STEP 6: Move PS33.66JBUPDAT.PUP to the directory UPDATE that you just created on the USB stick
STEP 7: Plug the USB stick into your PS3
STEP 8: Navigate to Settings Tab
STEP 9: Choose System Update
STEP 10: Choose Update via Storage Media
STEP 11: It will say it found Version 3.66-jb
STEP 12: Choose OK
STEP 13: Accept Conditions and Install Update
STEP 14: After less than a minute, your PS3 will update, beep 4 times then shut down.
STEP 15: Power up your PS3 (You will have to do it on the console and not by the controller)
STEP 16: Your PS3 is now jailbroken!