Mophie has introduced its new Juice Pack for the iPhone 3G. Like the company’s Juice Packs for iPhone and iPod touch, the iPhone 3G version houses a rechargeable lithium polymer battery within a soft touch, non-slip rear case. According to Mophie, the Juice Pack offers an additional 350 hours of standby time, 6 hours of talk time on 3G, 12 hours of talk time on 2G, 6 hours of Internet use on 3G, 8 hours of video playback, or 28 hours of audio…