Planetbeing iPhone Dev team member and the mind behind Linux on iPhone demonstrated the first iPhone 3G S unlock with Ultrasn0w. The unlock uses the same at+xlog vulnerability which is unlocking our iPhone 3G. This vulnerability was discovered by Oranav. So now this is the matter of time for getting our hands on iPhone 3G S unlock. Just wait for Apple release of firmware 3.1 and then wait for Dev team to release new pwnage tool which exclude your baseband update. Official Dev announcement ” Our ultrasn0w program uses the at+xlog crash as an injection vector of our unlocking payload — and it does so on the 3GS in exactly the same way as on the 3G! But this injection vector will be lost if you update to 3.1 using the official Apple IPSW, which updates the baseband. So stay away from official 3.1 IPSWs until we release the tools that let you update the firmware without updating the baseband.”
iPhone 3G S users : Capture Your 3GS iBEC and iBSS Signature Certificate and Save your Jailbreak.