Virtually identical to the same-named product for the original iPhone, ProClip’s Padded Holder with Tilt Swivel for iPhone 3G ($35) is a soft-coated, hard plastic adjustable car holder for the iPhone 3G.
As with all of ProClip’s products, you need to buy this piece along with a car-specific mounting bracket at a total cost of roughly $65, and get the ability to perfectly mount the device in whatever vehicle you may own.
The “Tilt Swivel” part of the name refers to a ball joint that enables the iPhone 3G to be turned or tilted on your preferred angle.