To everyone who has cleared their configuration and is now getting a segfault on startup with Maemo Mapper v1.2.3: please try typing the following commands (exactly as they appear - use copy/paste) into an xterm.

Code:

gconftool-2 -s -t string "/apps/maemo/maemo-mapper/units" "km"
gconftool-2 -s -t string "/apps/maemo/maemo-mapper/escape_key" "Toggle Tracks"

Then try starting Maemo Mapper. Let me know if this has any effect.