Heres a Screenshot of my current work on my Ardupilot Mega mission planner. If you want a look get it here http://vps.oborne.me/ArdupilotMegaPlanner.zip
This program captures lat,long and alt from google earth and creates a waypoint writer header file or you can write directly to the APM EEPROM. Using the latest command format. The command list is currently pulled from the APM source files, so it should always be up to date.
Requirements
.net framework 2.0+
Google earth browser plugin http://earth.google.com/plugin/
It should run under mono
Functions
Read from your current APM and edit
Write new missions directoly to your APM
Open other peoples EEPROM data, view there missions etc.
EEPROM is saved to file on read - for those more technicly savy. - and to share with friends
View EEPROM - ability to display some internaly saved setting like gyro offsets etc.
Write a Waypoint writter header file, for use with waypoint writter.
To use it.
open it.
click Open defines.h - and point it to your ardupilot mega source directory
select your com port
click either read or write (after adding a few WP's)