Apple on how to replace an original iPhone with a new 3G iPhone

Apple has posted a Support Document that explains exactly how to replace your original iPhone with a new 3G iPhone. Basically there are two tracks: 1) In the US you don't need your original SIM as your original "account information will be transferred to iPhone 3G's included SIM when you purchase iPhone 3G." 2) Outside the US, "you can use your original iPhone's SIM with iPhone 3G."

Once that's done it's just a matter of backing up your original iPhone to iTunes 7.7 and then restoring that backup to the new iPhone 3G. This should transfer all your saved SMS messages as well as email accounts, notes, etc. Once that's done you just need to erase the old iPhone with the new secure erase option.

[via Daring Fireball]