After the launch of 3G iPhone it is also available to purchase iPhone 3G Dock in Apple store.The item which was free with original iPhone now cost $29. Apple store also offer iPhone 3G Universal Dock Adapter 3-Pack for $9.
With the iPhone 3G Dock, you get easy access to a USB port for syncing or charging and an audio line out port for connecting to powered speakers. You can even conduct speakerphone calls with your iPhone 3G in its dock.
