Cute.
A concrete example of the fog of war:
You have "scout" units that, traditionally, report back. When a unit reports back, it tells you what it saw (and what others told it) while out in the field.
Your map consists of the known terrain (which doesn't change), and fuzzier information about enemy troops. The older the report, the more transparent the icon representing the troops is. Possibly some simple strait-line extrapolation is done if they where seen marching.
It would be a very different game than a normal RTS.
Edit: Another interesting read:
http://www.pointlesswasteoftime.com/games/wargames.html