It didn’t take so long to get this dream come true. Thanks to George Hotz it’s all possible now. What you need to do for getting your 3GS jailbroken is this:

To get started right now, go to purplera1n.com. Download it. Make sure you have windows(but not 7), the latest iTunes installed, and an iPhone 3GS with 3.0 firmware. Connect your iPhone normally. Click “make it ra1n”. Wait. On bootup, run Freeze, the purplera1n installer app. Hopefully you’ll figure out what to do from there.

If you need more info just go to the original blog.