Can someone tell me the easiest way to copy/transfer all your old text messages, etc from an existing iPhone (3G) to the new iPhone. Its for my mate and he seems unsure what to do (and I'm hurrying him along as I'm having his old phone 
My thoughts are that he can just back up his phone using iTunes and then restore to the new iPhone 4? or will it not restore to a new device/later model?

My thoughts are that he can just back up his phone using iTunes and then restore to the new iPhone 4? or will it not restore to a new device/later model?