If you have an old iPhone 2G (like Asa and Grace), then you can unlock them even with the latest firmware. Redmond Pie has a guide, but with the old bootrom, you basically
- Find a custom IPSW that you just use iTunes to install which is nice since it can be hacktivated
- Go through iTunes to install it with Option Restore
If you want to do your own customizations, then it is a little more complicated but here are the instructions
- You need an older version of Pwnage (1.5) that supports the original iPhone 2G
- Download the original IPSW for 3.1.3
- STart Pwnage and follow the directions to create your custom IPSW
- Go through iTunes to install with an Option Restore