This system is both well designed and fun to play with. That's not surprising, really, but worth mentioning. 
For my next tasks I'd like to play more with the map, what can be seen, and how some things appear on it. I'll make multiple posts to keep things organized. I hope that is correct practice.
I have set things up so that each play gets their own force. One of the goals of the mod is to allow forces to work together at various levels. I already have research completion sharing, for instance.
I would like to allow forces to share vision between each other.
My first thought to accomplish this was simply to see if an "on_charted" event existed. I didn't see one, but that rarely means much. Is there one?
I did see an event for when radars complete their scans, so that's a start.
One option I could attempt for everything else would be to constantly pulse chart updates around "allied" players and radars. I could adjust the amount of vision then, which is nice, but would also have to approximate when the radar actually does it's local pulse, as I know it's not constant. Is there an easy way to do that? Is the player's pulse constant?
I hope that's enough info so that someone can point me in the right direction.
Cheers!
-XComp
EDIT: Related Feature request: Map charting and drawing interfaces