My iPhone 3G lifetime when purchased on launch day was 9 days, 17 hours. What does that mean? And did others have different numbers? You can check this under USAGE in your iPhone 3G.
Did you by chance use your old SIM in your iPhone 3G? If so this includes talk time from your old phone and the iPhone. You should be able to reset it in the Settings.
No they gave me a completely new SIM.. and at the apple store I personally unsealed my phone. I noticed the battery life was half way when I turned it on the first time as well.