geohot has released the second revision of his windows iPhone 3GS jailbreak. This one includes:

• Vista, Windows 7, International, 64-bit support
• Less flakiness in the payload
• Cydia tar cleaned up
• Improved logging with slightly more useful errors
• New kernel patches, codesign errors gone. Props posixninja
• Added vm_map +x, passed vm_check
• No winterboard yet, but now that ball is in Saurik's court :-)
• Still in beta, use caution

You can download from purplera1n.com. Usage is the same so just follow our guide (windows) OR our OS X guide.

7/5 UPDATE: Mac version of purplera1n now available for download!