The Juice Pack for iPhone 3G is a rechargeable lithium polymer battery in the form of a non-slip, soft grip case.
It offers the following additional hours of use for Apple iPhone 3G :
• Standby Time – Up to 350 hours
• Talk Time – Up to 6 hours on 3G; Up to 12 hours on 2G
• Internet Use – Up to 6 hours on 3G; Up to 7 hours on Wi-Fi
• Audio Playback – Up to 28 hours
• Video Playback – Up to 8 hours
The Juice Pack for iPhone 3G is currently available for pre-order for US$99.95. The units will be sold “all juiced up and ready to go, straight out of the box.” The expected ship date is in late September.
More info here.