Today, PwnageTool / redsn0w / Sn0wBreeze were updated to jailbreak the new 4.3.3 update by Apple. This is an UN-TETHERED jailbreak.
Sn0wBreeze was updated toinclude the verizon iphone firmware 4.2.8 aswell.

Ultrasn0w was also updated to work with 4.3.3.

*Note* : This is not a new unlock in anyway!! It is just updating the already unlockable baseband's that are available.

So as per usual, to retain your baseband as an unlockable one.....AND update the firmware to the most recent, PwnageTool and Sn0wBreeze are your answer.
For those who do not need a carrier unlock, redsn0w is your pois0n.

Link's

redsn0w : Mac OSX / Windows

PwnageTool : Mac OSX only

Sn0wBreeze : Windows only