It seems you can jailbreak iOS 4.3.5/4.2.10 with redsn0w and here is how to do it!
First make sure you have iOS 4.3.5/4.2.10 installed and that you have 4.3.4/4.2.9 downloaded along with redsnow 9.8 B3 downloaded. Remember all download links will be down below! Please remember this is a tethered jailbreak meaning whenever you try and turn your phone on you will need to run redsn0w to make it show springboard.
Open redsn0w and hit browse and select the iOS 4.3.4 firmware and than hit next
Select Install Cydia and if you need to boot tethered unselect this option and select boot tethered and follow the instructions. Hit next and follow the online instructions and you are good an jailbroken!
iPhone 4 GSM 4.3.5 Download
iPhone 4 CDMA 4.2.10 Download
iPhone 4 GSM 4.3.4 Download
iPhone 4 CDMA 4.2.9 Download
Redsn0w Mac 9.8 B3 Download
Redsn0w Windows 9.8 B3 Download
Others have to be googled sorry.