In addition to all of the other problems reported with GPS, I think I found another one.

It appears that the gpsd daemon introduces a delay when reporting GPS data. As a result, mapping software (both maemo mapper and the built-in crappy one) show positions with a lag of a couple of seconds, sometimes more. This can translate into position inaccuracies of a couple hundred feet when driving at 70mph.

The reason I think the problem is in gpsd, is that there is a delay (as evidenced by NMEA timestamps) when running

/usr/libexec/navicore-gpsd-helper

but not when reading directly out of /dev/pgps.