Uniea's first rubber case is the U-Skin for iPhone 3G ($TBD), an inexpensive-looking, simple sleeve that comes in your choice of three colors and includes a clear screen protector. The only novelty here is the inclusion of a flip-open bottom that is compatible with the iPhone 3G Dock; a molded in rear texture with what appear to be horizontally running drips alternates between extruded and embossed to provide grip. Like the other Uniea cases we're…