Folks who prefer to carry their iPhone 3G in a case, but also want to keep it handy in the car will like this item.  USB Fever has released a leather case for the iPhone 3G that will connect directly to a vehicle mount.  According to USB Fever’s website, the case is made of high grade leather and features a mounting latch that is integrated directly into the back of the case.  This unique feature means that if you typically carry your iPhone in a case, you won’t need to remove it in order to use a vehicle mount.

Note that a mounting bracket does not come with the case, but USB Fever offers separate brackets for windshields, air vents, and lighter sockets.  They also offer a bracket for bicycles.