There have been many videos uploaded all over the web on iPhone being jailbroken , 
but if you are planning to jailbreak your phone , you would be surprised to know the jailbreaking tool is now available for iPhone 3G devices .
The Dev team is now providing redsn0w 0.9.5 BETA for download but cautions you if you are not a Jeakbreaking app developer , because the tool is available for iPhone developers and not for end users. And the tool is generally meant for iPhone developers who wish to fix their software before the end users get iPhone OS 4.0 on their device . They also say the Beta redsn0w does not perform hactivation , and you need a properly registered developer UDID with Apple to get past the activation screen and for the same reason the application is not available for the Windows version , since these apps are developed on MacOSX .
Please read the notes and cautions before accidently bricking you phone .
