Sherif Hashem which is a big iPhone hacker and developer and already worked with Dev Team and helped them in crashing Ultrasn0w 0.93, Has posted a video on Youtube showing how to Active iPhone 3GS / 3G and even iPhone 4 without having Original SIM to which the phone is locked. But in iPhone 4 you will need to cut the SIM Card.

Check The video here: http://www.youtube.com/watch?v=pA1bb9C7vNU&feature=player_embedded



Source: http://www.spiritjb.org/2010/07/how-to-activate-iphone-3g3gs4g-without.html