Finally got my Pi synced to the PPS pin on the GPS I plugged into it. It's currently indoors with a small ceramic antenna, but works.
Software is gpsd and chrony, hardware is a cheap ublox board with a hirose u.fl connector and a patch antenna, soon to be replaced with a chinese outdoor antenna.
The Pi is a model b, configured to use the standard UART (ttyS0) not the better one (ttyACM0), but that might need to change.
I think it'll be cool to add a little display with position/clock info.
@m0puh so if I understand what you're doing you are getting time from the GPS? Also, do you power the pi with a battery?
@K3LTC Yep, time and position.
I soldered the GPS module to the GPIO pins using a bit of jumper wire. The GPS outputs serial data once per second and has an extra output pulse every second which you can lock onto to get more precision.
You could definitely power the Pi with a battery, and if you did that you could probably have it act as a portable NTP server, or use it standalone. Maybe the best way to use that would be to set it up as a wireless access point too.