Even though the newly-released 4.3.4 update was supposed to correct the PDF vulnerability that allowed for jailbreaking, the folks at Redmond Pie managed to cobble together a tethered jailbreak with PwnageTool that'll get you right back into Cydia.

The new method works for all devices except the iPad 2. Of course, you should still stick with 4.3.3 if you don't want to bother with re-jailbreaking anytime your phone shuts off. [Redmond Pie via Engadget]