Case-mate has introduced its new line of cases and protective accessories for the iPhone 3G. The company’s Leather Cases for iPhone 3G come in three styles — Signature Series, Croc Embossed, and Carbon Fiber. All three varieties feature a leather exterior, a contoured fit, an impact-resistant interior plastic shell, open access to all ports and controls, and an included screen protector. The Signature Series will be available in red or…