Even though Apple just issued their 4.3.4 update for iOS on Friday, which patched the PDF exploit (disabling JailbreakMe 3.0), it has already been jailbroken, and the latest PwnageTool release can already install Cydia on the new firmware.
In addition to the PwnageTool release, it appears that popular jailbreak tool Redsn0w has also been updated with the ability to jailbreak the latest firmware. Unfortunately, the jailbreak is currently tethered (meaning you have to hook your iDevice up to your computer and use software to boot it every time it restarts), nevertheless, those of you excited to maintain your jailbroken status on the new firmware now have the ability to do so.
The jailbreak does not work with the iPad 2, and currently, the iPhone Dev Team continues to recommend that users do not yet update to 4.3.4, but remain on version 4.3.3, as the jailbreak work better on that version, and is untethered.