Although the iPhone 3G was only released a few days ago, the heavy hand of the hacker world has already accomplished the highly awaited (and expected) SIM unlocking feat. Basically the trick includes a "piggyback" SIM card which goes in between your SIM card and the phone itself, causing the phone to read any carrier’s SIM as one specific carrier’s SIM (which happens to be the same carrier that signed a deal with Apple to distribute the iPhone 3G).
Check out the video:
The Brazilian team who accomplished the SIM hack, led by Breno MacMasi, said the following:
Our procedure consist in using one SIM adapter to simulate a fake IMSI test card. Instead of the AT&T IMSI like in the universals.
(IMSI = International Mobile Subscriber Identity)
This isn’t available for the public yet, but I’m sure it’ll go on sale on some obscure website for $19.99 soon.