Can an iPhone be bought and used without a sim card or service?

Instead of buying an iPod touch, i was thinking about buying an iPhone 3g so i could use the camera. Can I use everything on the iPhone besides calling and texting on the iPhone (music, games, camera, wifi) without a sim card? Also, what is the difference between an iPhone 3g and an iPhone 3g s?Can an iPhone be bought and used without a sim card or service?I would wait for the next gen ipod touch.Can an iPhone be bought and used without a sim card or service?yep but it's expansive.Can an iPhone be bought and used without a sim card or service?For like the iPod function, but not calls. :P|||actually you can..he he..you just have to unlock and jailbreak your iphone...simply really just look it up on youtube.. : D