[img source : Apple.com]
iPhone 3GS users can now safely update to 3.1 firmware without updating the baseband (for unlock). If you are not the one to download all the various files and just want the ultimate result, these files are waiting for you to download! If you rather want to start from scratch, download Pwnage 3.1.3 tool for Mac.

Caution #1 : Please proceed further ONLY if you have an iPhone 3GS. iPhone 2G or 3G owners should follow this guide instead.
Caution #2 : A restore is going to wipe the …