GPS and Portability?

curious george asks: "I've always loved knowing exactly where I am in the world and it's becoming easier with the mainstream application of GPS receivers and other integrated technologies available on the consumer and prosumer market. However, finding those awesome accessories that seamlessly integrate with the laptop, mobile phone, or PDA are incredibly difficult. Does Slashdot know of any gadgets that can add the GPS capabilities found in most new vehicles to the mobile geek? Infrared, Bluetooth, USB, and other methods are abound, but what about compatibility between the Mac, Windows, Linux, and Symbian operating systems?"