Apple has just released iOS 4.3.4 through iTunes (4.2.9 for Verizon iPhone), which fixes the PDF exploit that allows JailbreakMe 3.0 to function, as well as providing bug fixes and improving stability.
Here are the direct links for iOS 4.3.4:
- iPhone 3GS
- iPhone 4 (GSM)
- iPad 2 (also iPad 2,2 and iPad 2,3)
- iPod touch 3rd gen
- iPod touch 4th gen
Also, iOS 4.2.9 has been updated for the Verizon iPhone, which you can download here.
Jailbreakers should stay away from this update until confirmation arises that there is a jailbreak available.