I don't think there is an alternative yet which is known to the general public. I have heard rumors that the military is working on a next generation system.
You interface to a GPS device with a UART, with or without an RS-232 transceiver. The data comes to you as a collection of ASCII strings. You need to write a program to parse the strings and extract the data you are looking for. In some cases the baudrate is quite high, like 38400 or 57600 and an offboard UART like the MAX3100 with it's 8 byte receive FIFO is a real advantage. Take it from me, the single buffered on board UART of the PIC, AVR, Z8, or 8051 families will have significant difficulty drinking from the fire hose, not to mention the RAM required for buffering.