I have just tested this and can confirm that the current latest version of Redsn0w can jailbreak iOS 4.3.3 (tethered) on iPhone 4, 3GS, iPod touch 4G/3G and other A4 based devices.
However the current version of Redsn0w 0.9.6 is limited to tethered jailbreak only, which means that you will have to boot your iOS device in tethered state on every reboot.
Cydia running on iOS 4.3.3
NOTE: Those of you who rely on a carrier unlock MUST STAY AWAY from Redsn0w and stock iOS 4.3.3 firmware.
Step 1: Download iOS 4.3.3 and iOS 4.3.2 (required by Redsn0w 0.9.6 for 4.3.3 jailbreak) for your version of iOS device.
Step 2: Update/Restore to iOS 4.3.3 firmware using the IPSW file you just downloaded via iTunes 10.2.2.
Step 3: Start Redsn0w and point it to the official iOS 4.3.2 firmware file (NOT iOS 4.3.3 file).
Step 4: Now select “Install Cydia” and click “Next”. Optionally (if available), you can also select any other option you like.
Step 5: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”.
At this stage you will be presented with a screen where you will be guided on how to enter DFU mode. Quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins.
Step 6: Sit back and enjoy while Redsn0w does the rest for you. Once done, your iPhone or iPod touch will restart automatically and you will find it jailbroken (tethered) on the latest iOS 4.3.3 firmware.
Step 7: Now from here onwards, whenever you want to do anything related to jailbreak like SSHing into your device, or running Cydia, you must first run your device in the so called “jailbroken state” on every reboot by using “Just boot tethered right now” option in Redsn0w.
Download iOS 4.3.3 for iPhone 4, 3GS, iPad, iPod touch
Download iOS 4.3.2 for iPhone 4, 3GS, iPad, iPod touch
Download Redsn0w 0.9.6rc14 for Windows
Download Redsn0w 0.9.6rc14 for Mac
Download iTunes 10.2.2 for Windows or Mac