So basically iPhone OS 3.0 when live yesterday and already the iPhone Dev Team seem to have cracked it open and found a security hole that allows jailbreaking.
And just so everyone knows, they have made a video demonstration which you can view below. The demo uses an iPhone 3G handset which we presume is locked to the dreaded AT&T, but using a T-Mobile SIM.
The video shows that once unlocked the iPhone 3G recognised the T-Mobile SIM and thus connects to the network, so hit up the video below and enjoy.