GPSD is a linux
/unix standard program that serves a single GPS connection to application software
. Most opensource GPS applications use GPSD. It normally resides at TCP port 2947.
GPSD uses single letters to return information, e.g. L for location returns latitude and longitude.
GPSD has a "raw" mode (using the "R" command) that sends NMEA data
(if you have a NMEA GPS) over the network connection. You can then use a virtual serial port to create a local or remote connection that other programs which need it to be a serial port can use. Note that you might need a modified GPSD or have to find some way to manually send the "R" command (e.g. in a DOS window do something like "echo R >com12:"). Normally you can create multiple virtual serial ports, each having the GPS datastream.
A free (but closed) virtual serial port driver is available from the HW Group http://www.hw-group.com/products/hw_vsp/index_en.html