A pocketpc can use GPS and through a bluetooth connection it can use GPRS.
There is even software available that lets you see the possition of others
and yourself on a map. Not sure of the name. If seen it on my search for
geocaching software. So geocaching would be a good search tem in google.

Boonie

I have done something a little similar.  At this stage I use SMS
instead of GPRS to send the position information, and the
position info I send is the names of the last 3 (distinct) cell
names and the cell ID of the serving cell.  Here in Australia,
all GSM networks broadcast cell names (town or suburb names) on
cell broadcast channel 50.

I have written my own software to do network monitoring.  The
software runs on a laptop from a DOS boot diskette with the
laptop connected to the phone via a serial cable.  The laptop
runs from a small 150W inverter using the car's 12V power.
Operation is automatic, with the network data being logged to
disk for later analysis.  The automatic sending of position
SMSs is optional, and uses a destination number and time period
(in minutes) from a configuration file.  I plan to incorporate
GPS position information in future.

If you have programming ability, you could build exactly the
application you want.

A major advantage of using a GSM terminal rather than a phone is
that the terminals run from 12V power, meaning that you don't
need to recharge the phone's battery periodically.  Battery
capacity is reduced considerably when a serial cable (or
Bluetooth) is used for constant data transfer.

John

Use a PocketPC with Bluetooth or Serial connection, with GPS connected
to PPC, running CoPilot mapping software, with the PPC and bluetooth
connected to phones GPRS.