iOS 4.3.4 is out and has been jailbroken already using the latest Redsn0w 0.9.8b3 release by Dev Team. Unlike the previous jailbreaks for iPhone 4 / 3GS, iPod Touch & iPad on iOS 4.3.x, this one is a tethered jailbreak since the existing untethered venerability discovered by @i0n1c has been patched by Apple in iOS 4.3.4 along with the PDF vulnerability found in iOS 4.3 to 4.3.3 used in JailbreakMe 3.0 by @comex. Nonetheless, Limera1n exploit still works on iOS 4.3.4 for all devices except the iPad 2 which can be applied to jailbreak your device using the latest Redsn0w.
Complete Instructions Here:
How To: Jailbreak iOS 4.3.4 On iPhone 4 / 3GS, iPod Touch & iPad [Redsn0w 0.9.8b3] | iThinkDifferent.